fix: handle conditional breaks in nested switch statement cases

src/ast/ExecutionContext.ts

@@ -21,6 +21,7 @@ interface ControlFlowContext {
 }
 
 export interface InclusionContext extends ControlFlowContext {
+	existedBroken: boolean;
 	includedCallArguments: Set<Entity>;
 }
 
@@ -37,6 +38,7 @@ export interface HasEffectsContext extends ControlFlowContext {
 export function createInclusionContext(): InclusionContext {
 	return {
 		brokenFlow: BROKEN_FLOW_NONE,
+		existedBroken: false,
 		includedCallArguments: new Set(),
 		includedLabels: new Set()
 	};

src/ast/nodes/IfStatement.ts

@@ -2,6 +2,7 @@ import type MagicString from 'magic-string';
 import type { RenderOptions } from '../../utils/renderHelpers';
 import type { DeoptimizableEntity } from '../DeoptimizableEntity';
 import {
+	BROKEN_FLOW_BREAK_CONTINUE,
 	BROKEN_FLOW_NONE,
 	type HasEffectsContext,
 	type InclusionContext
@@ -173,10 +174,13 @@ export default class IfStatement extends StatementBase implements DeoptimizableE
 			this.consequent.include(context, false, { asSingleStatement: true });
 			// eslint-disable-next-line unicorn/consistent-destructuring
 			consequentBrokenFlow = context.brokenFlow;
+			context.existedBroken ||= consequentBrokenFlow === BROKEN_FLOW_BREAK_CONTINUE;
 			context.brokenFlow = brokenFlow;
 		}
 		if (this.alternate?.shouldBeIncluded(context)) {
 			this.alternate.include(context, false, { asSingleStatement: true });
+			// eslint-disable-next-line unicorn/consistent-destructuring
+			context.existedBroken ||= context.brokenFlow === BROKEN_FLOW_BREAK_CONTINUE;
 			context.brokenFlow =
 				// eslint-disable-next-line unicorn/consistent-destructuring
 				context.brokenFlow < consequentBrokenFlow ? context.brokenFlow : consequentBrokenFlow;

src/ast/nodes/SwitchCase.ts

@@ -5,7 +5,12 @@ import {
 	type RenderOptions,
 	renderStatementList
 } from '../../utils/renderHelpers';
-import type { HasEffectsContext, InclusionContext } from '../ExecutionContext';
+import {
+	BROKEN_FLOW_BREAK_CONTINUE,
+	BROKEN_FLOW_ERROR_RETURN_LABEL,
+	type HasEffectsContext,
+	type InclusionContext
+} from '../ExecutionContext';
 import type * as NodeType from './NodeType';
 import {
 	type ExpressionNode,
@@ -36,6 +41,9 @@ export default class SwitchCase extends NodeBase {
 			if (includeChildrenRecursively || node.shouldBeIncluded(context))
 				node.include(context, includeChildrenRecursively);
 		}
+		if (context.existedBroken && context.brokenFlow === BROKEN_FLOW_ERROR_RETURN_LABEL) {
+			context.brokenFlow = BROKEN_FLOW_BREAK_CONTINUE;
+		}
 	}
 
 	render(code: MagicString, options: RenderOptions, nodeRenderOptions?: NodeRenderOptions): void {

test/function/samples/switch-break/_config.js

@@ -0,0 +1,3 @@
+module.exports = {
+	description: 'if switch does not always throw an error, retain the following break'
+};

test/function/samples/switch-break/main.js

@@ -0,0 +1,21 @@
+function issue(obj) {
+	switch (obj.field1) {
+		case 'baz':
+			switch (obj.field2) {
+				case 'value': {
+					if (obj.field1) {
+						if (obj.field1) {
+							break;
+						}
+					}
+					throw new Error(`error 1`);
+				}
+				default:
+					throw new Error(`error 2`);
+			}
+			break; // retained
+		default:
+			throw new Error('error 3');
+	}
+}
+issue({ field1: 'baz', field2: 'value' });