flow: Enable 'uninitialized-instance-property' lint

.flowconfig

@@ -28,7 +28,7 @@ implicit-inexact-object=error
 unnecessary-optional-chain=error
 unnecessary-invariant=off
 signature-verification-failure=error
-uninitialized-instance-property=off
+uninitialized-instance-property=error
 non-array-spread=error
 
 [options]

src/language/parser.js

@@ -1,6 +1,7 @@
 // @flow strict
 
 import inspect from '../jsutils/inspect';
+import invariant from '../jsutils/invariant';
 import defineToJSON from '../jsutils/defineToJSON';
 import { Source } from './source';
 import { type GraphQLError } from '../error/GraphQLError';
@@ -171,11 +172,10 @@ class Parser {
 
   constructor(source: string | Source, options?: ParseOptions) {
     const sourceObj = typeof source === 'string' ? new Source(source) : source;
-    if (!(sourceObj instanceof Source)) {
-      throw new TypeError(
-        `Must provide Source. Received: ${inspect(sourceObj)}`,
-      );
-    }
+    invariant(
+      sourceObj instanceof Source,
+      `Must provide Source. Received: ${inspect(sourceObj)}`,
+    );
 
     this._lexer = createLexer(sourceObj);
     this._options = options || {};

src/type/definition.js

@@ -555,13 +555,13 @@ export class GraphQLScalarType {
   extensionASTNodes: ?$ReadOnlyArray<ScalarTypeExtensionNode>;
 
   constructor(config: GraphQLScalarTypeConfig<*, *>): void {
+    const parseValue = config.parseValue || identityFunc;
     this.name = config.name;
     this.description = config.description;
     this.serialize = config.serialize || identityFunc;
-    this.parseValue = config.parseValue || identityFunc;
+    this.parseValue = parseValue;
     this.parseLiteral =
-      config.parseLiteral ||
-      (node => this.parseValue(valueFromASTUntyped(node)));
+      config.parseLiteral || (node => parseValue(valueFromASTUntyped(node)));
 
     this.astNode = config.astNode;
     this.extensionASTNodes = undefineIfEmpty(config.extensionASTNodes);
@@ -1155,7 +1155,7 @@ export class GraphQLEnumType /* <T> */ {
     this.description = config.description;
     this.astNode = config.astNode;
     this.extensionASTNodes = undefineIfEmpty(config.extensionASTNodes);
-    this._values = defineEnumValues(this, config.values);
+    this._values = defineEnumValues(this.name, config.values);
     this._valueLookup = new Map(
       this._values.map(enumValue => [enumValue.value, enumValue]),
     );
@@ -1232,22 +1232,22 @@ defineToStringTag(GraphQLEnumType);
 defineToJSON(GraphQLEnumType);
 
 function defineEnumValues(
-  type: GraphQLEnumType,
+  typeName: string,
   valueMap: GraphQLEnumValueConfigMap /* <T> */,
 ): Array<GraphQLEnumValue /* <T> */> {
   invariant(
     isPlainObj(valueMap),
-    `${type.name} values must be an object with value names as keys.`,
+    `${typeName} values must be an object with value names as keys.`,
   );
   return objectEntries(valueMap).map(([valueName, value]) => {
     invariant(
       isPlainObj(value),
-      `${type.name}.${valueName} must refer to an object with a "value" key ` +
+      `${typeName}.${valueName} must refer to an object with a "value" key ` +
         `representing an internal value but got: ${inspect(value)}.`,
     );
     invariant(
       !('isDeprecated' in value),
-      `${type.name}.${valueName} should provide "deprecationReason" instead of "isDeprecated".`,
+      `${typeName}.${valueName} should provide "deprecationReason" instead of "isDeprecated".`,
     );
     return {
       name: valueName,

src/type/schema.js

@@ -165,17 +165,12 @@ export class GraphQLSchema {
     this.extensionASTNodes = config.extensionASTNodes;
 
     // Build type map now to detect any errors within this schema.
-    let initialTypes: Array<?GraphQLNamedType> = [
-      this.getQueryType(),
-      this.getMutationType(),
-      this.getSubscriptionType(),
+    const initialTypes: Array<?GraphQLNamedType> = [
+      this._queryType,
+      this._mutationType,
+      this._subscriptionType,
       __Schema,
-    ];
-
-    const types = config.types;
-    if (types) {
-      initialTypes = initialTypes.concat(types);
-    }
+    ].concat(config.types);
 
     // Keep track of all types referenced within the schema.
     let typeMap: TypeMap = Object.create(null);