diff --git a/.vscode/launch.json b/.vscode/launch.json
new file mode 100644
index 000000000..197e04802
--- /dev/null
+++ b/.vscode/launch.json
@@ -0,0 +1,15 @@
+{
+	// Use IntelliSense to learn about possible attributes.
+	// Hover to view descriptions of existing attributes.
+	// For more information, visit: https://go.microsoft.com/fwlink/?linkid=830387
+	"version": "0.2.0",
+	"configurations": [
+		{
+			"type": "pwa-chrome",
+			"request": "launch",
+			"name": "Launch Chrome against localhost",
+			"url": "http://localhost:3000",
+			"webRoot": "${workspaceFolder}"
+		}
+	]
+}
diff --git a/cypress/e2e/diagramUpdate.spec.ts b/cypress/e2e/diagramUpdate.spec.ts
index b0075aa2f..a4c3d50af 100644
--- a/cypress/e2e/diagramUpdate.spec.ts
+++ b/cypress/e2e/diagramUpdate.spec.ts
@@ -3,6 +3,7 @@ describe('Auto sync tests', () => {
 		cy.clearLocalStorage();
 		cy.visit('/');
 	});
+
 	it('should dim diagram when code is edited', () => {
 		cy.contains('Auto sync').click();
 		cy.get('#view').should('not.have.class', 'outOfSync');
@@ -40,4 +41,17 @@ describe('Auto sync tests', () => {
 		cy.get('#editor').type(`{uparrow}{${cmd}}/`);
 		cy.get('#view').contains('Car').should('exist');
 	});
+
+	it('supports editing code when code is incorrect', () => {
+		cy.visit(
+			'/edit#pako:eNpljjEKwzAMRa8SNOcEnlt6gK5eVFvYJsgOqkwpIXevg9smEE1PnyfxF3DFExgISW-CczQ2D21cYU7a-SGYXRwyvTp9jUhuKlVP-eHy7zA-leQsMEmg_QOM0BLG5FujZVMsaCQmC6ahR5ks2Lw2r84ela4-aREwKpVGwKrl_s7ut3fnkjAIcg_XDzuaUhs'
+		);
+		cy.get('#editor').type(`{enter}branch test`);
+		cy.get('#editor').contains('branch test').should('exist');
+		cy.get('#errorContainer')
+			.contains(
+				'Error: Trying to checkout branch which is not yet created. (Help try using "branch master")'
+			)
+			.should('exist');
+	});
 });
diff --git a/cypress/snapshots.js b/cypress/snapshots.js
index 05581857a..7e54bcb93 100644
--- a/cypress/snapshots.js
+++ b/cypress/snapshots.js
@@ -16,7 +16,7 @@ module.exports = {
       "1": "{\"code\":\"graph TD\\n    A[Party] -->|Get money| B(Go shopping!!)\\n    \",\"mermaid\":\"{\\n  \\\"theme\\\": \\\"forest\\\",\\n  \\\"test\\\": \\\"hello world\\\"\\n}\",\"updateEditor\":false,\"autoSync\":true,\"updateDiagram\":true,\"loader\":{\"type\":\"files\",\"config\":{\"codeURL\":\"https://gist.githubusercontent.com/sidharthv96/6268a23e673a533dcb198f241fd7012a/raw/4eb03887e6a41397e80bdcdbf94017c498f8f1e2/code.mmd\",\"configURL\":\"https://gist.githubusercontent.com/sidharthv96/6268a23e673a533dcb198f241fd7012a/raw/4eb03887e6a41397e80bdcdbf94017c498f8f1e2/config.json\"}}}"
     }
   },
-  "__version": "10.2.0",
+  "__version": "10.3.0",
   "Auto sync tests": {
     "should dim diagram when code is edited": {
       "1": "{\"code\":\"graph TD\\n    A[Christmas] -->|Get money| B(Go shopping)\\n    B --> C{Let me think}\\n    C -->|One| D[Laptop]\\n    C -->|Two| E[iPhone]\\n    C -->|Three| F[fa:fa-car Car]\\n    C --> Test\",\"mermaid\":\"{\\n  \\\"theme\\\": \\\"default\\\"\\n}\",\"updateEditor\":false,\"autoSync\":false,\"updateDiagram\":false}"
diff --git a/src/lib/components/actions.svelte b/src/lib/components/actions.svelte
index 7a23e0149..e504de0dd 100644
--- a/src/lib/components/actions.svelte
+++ b/src/lib/components/actions.svelte
@@ -4,7 +4,7 @@
 	import Card from '$lib/components/card/card.svelte';
 	import { krokiRendererUrl, rendererUrl } from '$lib/util/env';
 	import { pakoSerde } from '$lib/util/serde';
-	import { serializedState, codeStore } from '$lib/util/state';
+	import { stateStore } from '$lib/util/state';
 	import { toBase64 } from 'js-base64';
 	import moment from 'moment';
 
@@ -57,6 +57,7 @@
 		const svgEl: HTMLElement = document
 			.querySelector('#container svg')
 			.cloneNode(true) as HTMLElement;
+		svgEl.setAttribute('xmlns:xlink', 'http://www.w3.org/1999/xlink');
 		const fontAwesomeCdnUrl = Array.from(document.head.getElementsByTagName('link'))
 			.map((l) => l.href)
 			.find((h) => h && h.includes('font-awesome'));
@@ -130,10 +131,10 @@
 	};
 
 	let gistURL = '';
-	codeStore.subscribe((state) => {
-		if (state.loader?.type === 'gist') {
+	stateStore.subscribe(({ loader }) => {
+		if (loader?.type === 'gist') {
 			// @ts-ignore Gist will have url
-			gistURL = state.loader.config.url;
+			gistURL = loader.config.url;
 		}
 	});
 
@@ -155,11 +156,11 @@
 	if (browser && ['mermaid.live', 'netlify'].some((path) => window.location.host.includes(path))) {
 		isNetlify = true;
 	}
-	serializedState.subscribe((encodedState: string) => {
-		iUrl = `${rendererUrl}/img/${encodedState}`;
-		svgUrl = `${rendererUrl}/svg/${encodedState}`;
-		krokiUrl = `${krokiRendererUrl}/mermaid/svg/${pakoSerde.serialize($codeStore.code)}`;
-		mdCode = `[![](${iUrl})](${window.location.protocol}//${window.location.host}${window.location.pathname}#${encodedState})`;
+	stateStore.subscribe(({ code, serialized }) => {
+		iUrl = `${rendererUrl}/img/${serialized}`;
+		svgUrl = `${rendererUrl}/svg/${serialized}`;
+		krokiUrl = `${krokiRendererUrl}/mermaid/svg/${pakoSerde.serialize(code)}`;
+		mdCode = `[![](${iUrl})](${window.location.protocol}//${window.location.host}${window.location.pathname}#${serialized})`;
 	});
 </script>
 
diff --git a/src/lib/components/editor.svelte b/src/lib/components/editor.svelte
index 536bb427a..1399a3506 100644
--- a/src/lib/components/editor.svelte
+++ b/src/lib/components/editor.svelte
@@ -1,6 +1,6 @@
 <script lang="ts">
 	import type { EditorEvents } from '$lib/types';
-	import { codeStore } from '$lib/util/state';
+	import { stateStore } from '$lib/util/state';
 	import { themeStore } from '$lib/util/theme';
 	import type monaco from 'monaco-editor';
 	import { createEventDispatcher, onMount } from 'svelte';
@@ -21,17 +21,16 @@
 		theme: 'mermaid',
 		overviewRulerLanes: 0
 	};
-	export let errorMarkers: monaco.editor.IMarkerData[] = [];
 	let oldText = text;
 	$: editor && Monaco?.editor.setModelLanguage(editor.getModel(), language);
 	$: {
 		if (text !== oldText) {
-			if ($codeStore.updateEditor) {
+			if ($stateStore.updateEditor) {
 				editor?.setValue(text);
 			}
 			oldText = text;
 		}
-		editor && Monaco?.editor.setModelMarkers(editor.getModel(), 'test', errorMarkers);
+		editor && Monaco?.editor.setModelMarkers(editor.getModel(), 'test', $stateStore.errorMarkers);
 	}
 
 	themeStore.subscribe(({ isDark }) => {
diff --git a/src/lib/components/history/history.svelte b/src/lib/components/history/history.svelte
index c31e72f3c..6ee607746 100644
--- a/src/lib/components/history/history.svelte
+++ b/src/lib/components/history/history.svelte
@@ -1,6 +1,6 @@
 <script lang="ts">
 	import Card from '$lib/components/card/card.svelte';
-	import { codeStore, getStateString } from '$lib/util/state';
+	import { inputStateStore, getStateString } from '$lib/util/state';
 	import {
 		addHistoryEntry,
 		historyModeStore,
@@ -37,7 +37,7 @@
 		const previousState: string = getPreviousState(auto);
 		if (previousState !== currentState) {
 			addHistoryEntry({
-				state: $codeStore,
+				state: $inputStateStore,
 				time: Date.now(),
 				type: auto ? 'auto' : 'manual'
 			});
@@ -54,7 +54,7 @@
 	};
 
 	const restoreHistory = (state: State): void => {
-		codeStore.set({ ...state, updateEditor: true, updateDiagram: true });
+		inputStateStore.set({ ...state, updateEditor: true, updateDiagram: true });
 	};
 
 	const relativeTime = (time: number) => {
diff --git a/src/lib/components/preset.svelte b/src/lib/components/preset.svelte
index 6a4eddc85..2c31cbaf8 100644
--- a/src/lib/components/preset.svelte
+++ b/src/lib/components/preset.svelte
@@ -95,7 +95,10 @@
 	};
 
 	const loadSampleDiagram = (diagramType: string): void => {
-		updateCode(samples[diagramType], true, true);
+		updateCode(samples[diagramType], {
+			updateDiagram: true,
+			updateEditor: true
+		});
 	};
 </script>
 
diff --git a/src/lib/components/view.svelte b/src/lib/components/view.svelte
index 6bb96687c..a4036093e 100644
--- a/src/lib/components/view.svelte
+++ b/src/lib/components/view.svelte
@@ -1,7 +1,5 @@
 <script lang="ts">
-	import { errorStore } from '$lib/util/error';
-
-	import { codeStore } from '$lib/util/state';
+	import { inputStateStore, stateStore } from '$lib/util/state';
 	import { onMount } from 'svelte';
 	import mermaid from 'mermaid';
 
@@ -13,11 +11,16 @@
 	let outOfSync = false;
 	let manualUpdate = true;
 	onMount(() => {
-		codeStore.subscribe((state) => {
+		stateStore.subscribe((state) => {
+			if (state.error !== undefined) {
+				error = true;
+				return;
+			}
+			error = false;
 			try {
 				if (container && state && (state.updateDiagram || state.autoSync)) {
 					if (!state.autoSync) {
-						$codeStore.updateDiagram = false;
+						$inputStateStore.updateDiagram = false;
 					}
 					outOfSync = false;
 					manualUpdate = true;
@@ -31,7 +34,10 @@
 					delete container.dataset.processed;
 					mermaid.initialize(Object.assign({}, JSON.parse(state.mermaid)));
 					mermaid.render('graph-div', code, (svgCode) => {
-						container.innerHTML = svgCode;
+						if (svgCode.length > 0) {
+							console.log(svgCode);
+							container.innerHTML = svgCode;
+						}
 					});
 					view.parentElement.scrollTop = scroll;
 					error = false;
@@ -45,24 +51,19 @@
 				error = true;
 			}
 		});
-		errorStore.subscribe((err) => {
-			if (typeof err === 'undefined') {
-				error = false;
-			} else {
-				error = true;
-				console.log('Error: ', err);
-			}
-		});
 	});
 </script>
 
+{#if error && $stateStore.error instanceof Error}
+	<div class="p-2 text-red-600" id="errorContainer">{$stateStore.error}</div>
+{/if}
+
 <div id="view" bind:this={view} class="p-2" class:error class:outOfSync>
 	<div id="container" bind:this={container} class="flex-1 overflow-auto" />
 </div>
 
 <style>
 	#view {
-		border: 1px solor darkred;
 		flex: 1;
 	}
 	.error,
diff --git a/src/lib/types.d.ts b/src/lib/types.d.ts
index 7db225f5a..0f750f9e7 100644
--- a/src/lib/types.d.ts
+++ b/src/lib/types.d.ts
@@ -6,6 +6,16 @@ export interface Locals {
 	userid: string;
 }
 
+export interface MarkerData {
+	severity: number;
+	message: string;
+	source?: string;
+	startLineNumber: number;
+	startColumn: number;
+	endLineNumber: number;
+	endColumn: number;
+}
+
 export interface EditorUpdateEvent {
 	text: string;
 }
@@ -32,6 +42,12 @@ export interface State {
 	loader?: LoaderConfig;
 }
 
+export interface ValidatedState extends State {
+	error: any;
+	errorMarkers: MarkerData[];
+	serialized: string;
+}
+
 export interface GistLoaderConfig {
 	url: string;
 }
@@ -64,4 +80,4 @@ export interface DocConfig {
 	};
 }
 
-type Loader = (url: string) => Promise<State>;
+export type Loader = (url: string) => Promise<State>;
diff --git a/src/lib/util/error.ts b/src/lib/util/error.ts
deleted file mode 100644
index 43829bf65..000000000
--- a/src/lib/util/error.ts
+++ /dev/null
@@ -1,3 +0,0 @@
-import { writable } from 'svelte/store';
-
-export const errorStore = writable(undefined);
diff --git a/src/lib/util/fileLoaders/loader.ts b/src/lib/util/fileLoaders/loader.ts
index 02b73aa2f..2f8b48e15 100644
--- a/src/lib/util/fileLoaders/loader.ts
+++ b/src/lib/util/fileLoaders/loader.ts
@@ -54,5 +54,4 @@ export const loadDataFromUrl = async (): Promise<void> => {
 			updateDiagram: true,
 			updateEditor: true
 		});
-	// window.location.search = '';
 };
diff --git a/src/lib/util/state.ts b/src/lib/util/state.ts
index 73157a543..6770cf75c 100644
--- a/src/lib/util/state.ts
+++ b/src/lib/util/state.ts
@@ -1,9 +1,11 @@
 import { writable, get, derived } from 'svelte/store';
-import type { Readable } from 'svelte/store';
 import { persist, localStorage } from '@macfja/svelte-persistent-store';
-import type { State } from '$lib/types';
 import { saveStatistics } from './stats';
 import { serializeState, deserializeState } from './serde';
+import mermaid from 'mermaid';
+
+import type { Readable } from 'svelte/store';
+import type { MarkerData, State, ValidatedState } from '$lib/types';
 
 export const defaultState: State = {
 	code: `graph TD
@@ -36,9 +38,42 @@ const urlParseFailedState = `graph TD
     G --> |"No :("| H(Try using the Timeline tab in History <br/>from same browser you used to create the diagram.)
     click D href "https://github.com/mermaid-js/mermaid-live-editor/issues/new?assignees=&labels=bug&template=bug_report.md&title=Broken%20link" "Raise issue"`;
 
-export const codeStore = persist(writable(defaultState), localStorage(), 'codeStore');
-export const serializedState: Readable<string> = derived([codeStore], ([code], set) => {
-	set(serializeState(code));
+// inputStateStore handles all updates and is shared externally when exporting via URL, History, etc.
+export const inputStateStore = persist(writable(defaultState), localStorage(), 'codeStore');
+
+// All internal reads should be done via stateStore, but it should not be persisted/shared externally.
+export const stateStore: Readable<ValidatedState> = derived([inputStateStore], ([state]) => {
+	const processed: ValidatedState = {
+		...state,
+		serialized: '',
+		errorMarkers: [],
+		error: undefined
+	};
+	// No changes should be done to fields part of `state`.
+	try {
+		processed.serialized = serializeState(state);
+		mermaid.parse(state.code);
+		JSON.parse(state.mermaid);
+	} catch (e) {
+		processed.error = e;
+		console.error(e);
+		if (e.hash) {
+			try {
+				const marker: MarkerData = {
+					severity: 8, // Error
+					startLineNumber: e.hash.loc.first_line,
+					startColumn: e.hash.loc.first_column,
+					endLineNumber: e.hash.loc.last_line,
+					endColumn: (e.hash.loc.last_column as number) + 1,
+					message: e.str
+				};
+				processed.errorMarkers = [marker];
+			} catch (err) {
+				console.error('Error without line helper', err);
+			}
+		}
+	}
+	return processed;
 });
 
 export const loadState = (data: string): void => {
@@ -57,30 +92,33 @@ export const loadState = (data: string): void => {
 		) {
 			delete mermaidConfig.securityLevel; // Prevent setting overriding securityLevel when loading state to mitigate possible XSS attack
 		}
-
 		state.mermaid = JSON.stringify(mermaidConfig, null, 2);
 	} catch (e) {
-		state = get(codeStore);
+		state = get(inputStateStore);
 		if (data) {
 			console.error('Init error', e);
 			state.code = urlParseFailedState;
+			state.mermaid = defaultState.mermaid;
 		}
 	}
 	updateCodeStore({ ...state, updateEditor: true });
 };
 
 export const updateCodeStore = (newState: State): void => {
-	codeStore.update((state) => {
+	inputStateStore.update((state) => {
 		return { ...state, ...newState };
 	});
 };
 
 let prompted = false;
-export const updateCode = (code: string, updateEditor: boolean, updateDiagram = false): void => {
+export const updateCode = (
+	code: string,
+	{ updateEditor, updateDiagram = false }: { updateEditor: boolean; updateDiagram?: boolean }
+): void => {
 	saveStatistics(code);
 	const lines = (code.match(/\n/g) || '').length + 1;
 
-	if (lines > 50 && !prompted && get(codeStore).autoSync) {
+	if (lines > 50 && !prompted && get(stateStore).autoSync) {
 		const turnOff = confirm(
 			'Long diagram detected. Turn off Auto Sync? Click the sync logo to manually sync.'
 		);
@@ -92,19 +130,19 @@ export const updateCode = (code: string, updateEditor: boolean, updateDiagram =
 		}
 	}
 
-	codeStore.update((state) => {
+	inputStateStore.update((state) => {
 		return { ...state, code, updateEditor, updateDiagram };
 	});
 };
 
 export const updateConfig = (config: string, updateEditor: boolean): void => {
-	codeStore.update((state) => {
+	inputStateStore.update((state) => {
 		return { ...state, mermaid: config, updateEditor };
 	});
 };
 
 export const toggleDarkTheme = (dark: boolean): void => {
-	codeStore.update((state) => {
+	inputStateStore.update((state) => {
 		const config = JSON.parse(state.mermaid);
 		if (!config.theme || ['dark', 'default'].includes(config.theme)) {
 			config.theme = dark ? 'dark' : 'default';
@@ -115,11 +153,11 @@ export const toggleDarkTheme = (dark: boolean): void => {
 };
 
 export const initURLSubscription = (): void => {
-	serializedState.subscribe((state: string) => {
-		history.replaceState(undefined, undefined, `#${state}`);
+	stateStore.subscribe(({ serialized }) => {
+		history.replaceState(undefined, undefined, `#${serialized}`);
 	});
 };
 
 export const getStateString = (): string => {
-	return JSON.stringify(get(codeStore));
+	return JSON.stringify(get(inputStateStore));
 };
diff --git a/src/routes/edit.svelte b/src/routes/edit.svelte
index 9e4041eb4..3ec957f41 100644
--- a/src/routes/edit.svelte
+++ b/src/routes/edit.svelte
@@ -6,17 +6,12 @@
 	import View from '$lib/components/view.svelte';
 	import Card from '$lib/components/card/card.svelte';
 	import History from '$lib/components/history/history.svelte';
-	import { updateCode, updateConfig, codeStore, serializedState } from '$lib/util/state';
+	import { updateCode, updateConfig, inputStateStore, stateStore } from '$lib/util/state';
 	import { initHandler, syncDiagram } from '$lib/util/util';
-	import { errorStore } from '$lib/util/error';
 	import { onMount } from 'svelte';
-	import mermaid from 'mermaid';
-	import type monaco from 'monaco-editor';
 	import type { EditorUpdateEvent, State, Tab, DocConfig } from '$lib/types';
 	import { base } from '$app/paths';
 
-	serializedState; // Weird fix for error > serializedState is not defined. Treeshaking?
-
 	type Modes = 'code' | 'config';
 	type Languages = 'mermaid' | 'json';
 
@@ -68,17 +63,16 @@
 	let text = '';
 	let docURL = docURLBase;
 	let language: Languages = 'mermaid';
-	let errorMarkers: monaco.editor.IMarkerData[] = [];
 	$: language = languageMap[selectedMode];
 	$: {
 		if (selectedMode === 'code') {
-			text = $codeStore.code;
+			text = $stateStore.code;
 		} else {
-			text = $codeStore.mermaid;
+			text = $stateStore.mermaid;
 		}
 	}
 
-	codeStore.subscribe((state: State) => {
+	stateStore.subscribe((state: State) => {
 		if (state.updateEditor) {
 			text = selectedMode === 'code' ? state.code : state.mermaid;
 		}
@@ -91,7 +85,7 @@
 	});
 	const tabSelectHandler = (message: CustomEvent<Tab>) => {
 		selectedMode = message.detail.id === 'code' ? 'code' : 'config';
-		$codeStore.updateEditor = true;
+		$inputStateStore.updateEditor = true;
 	};
 	const tabs: Tab[] = [
 		{
@@ -106,55 +100,26 @@
 		}
 	];
 
-	const handleCodeUpdate = (code: string): void => {
-		mermaid.parse(code);
-		updateCode(code, false);
-	};
-
-	const handleConfigUpdate = (config: string): void => {
-		JSON.parse(config);
-		updateConfig(config, false);
-	};
-
 	const updateHandler = (message: CustomEvent<EditorUpdateEvent>) => {
-		try {
-			if (selectedMode === 'code') {
-				handleCodeUpdate(message.detail.text);
-			} else {
-				handleConfigUpdate(message.detail.text);
-			}
-			errorStore.set(undefined);
-			errorMarkers = [];
-		} catch (e) {
-			errorStore.set(e);
-			if (e.hash) {
-				const marker: monaco.editor.IMarkerData = {
-					severity: 8, //Error
-					startLineNumber: e.hash.loc.first_line,
-					startColumn: e.hash.loc.first_column,
-					endLineNumber: e.hash.loc.last_line,
-					endColumn: (e.hash.loc.last_column as number) + 1,
-					message: e.str
-				};
-				errorMarkers.push(marker);
-				// Clear all previous errors before this error.
-				errorMarkers = errorMarkers.filter(
-					(m) => m.startLineNumber >= marker.startLineNumber && m.startColumn >= marker.startColumn
-				);
-			}
-			console.error(e);
+		const code = message.detail.text;
+		if (selectedMode === 'code') {
+			updateCode(code, {
+				updateEditor: false
+			});
+		} else {
+			updateConfig(code, false);
 		}
 	};
 
 	const viewDiagram = () => {
-		window.open(`${base}/view#${$serializedState}`, '_blank').focus();
+		window.open(`${base}/view#${$stateStore.serialized}`, '_blank').focus();
 	};
 
 	onMount(async () => {
 		await initHandler();
 		const resizer = document.getElementById('resizeHandler');
 		const element = document.getElementById('editorPane');
-		const resize = (e) => {
+		const resize = (e: { pageX: number }) => {
 			const newWidth = e.pageX - element.getBoundingClientRect().left;
 			if (newWidth > 50) {
 				element.style.width = `${newWidth}px`;
@@ -184,13 +149,13 @@
 								<span> Auto sync</span>
 								<input
 									type="checkbox"
-									class="toggle {$codeStore.autoSync ? 'btn-secondary' : 'toggle-primary'} ml-1"
+									class="toggle {$stateStore.autoSync ? 'btn-secondary' : 'toggle-primary'} ml-1"
 									id="autoSync"
-									bind:checked={$codeStore.autoSync} />
+									bind:checked={$inputStateStore.autoSync} />
 							</label>
 						</div>
 
-						{#if !$codeStore.autoSync}
+						{#if !$stateStore.autoSync}
 							<button
 								class="btn btn-secondary btn-xs mr-1"
 								title="Sync Diagram"
@@ -204,7 +169,7 @@
 					</div>
 				</div>
 
-				<Editor on:update={updateHandler} {language} bind:text {errorMarkers} />
+				<Editor on:update={updateHandler} {language} bind:text />
 			</Card>
 
 			<div class="-mt-2">