TypeScript Error reproduciton

app.js

import {vextend} from './func'
// hover on vextend
export var a = vextend({
  watch: {
    data1(val) {
      this.data2 = 1
    },
    data2(val) { }
  }
})

func.ts

interface ComponentOptions<V> {
  watch: Record<string, WatchHandler<any>>;
}
type WatchHandler<T> = (val: T) => void;
declare function extend(options: ComponentOptions<{}>): void;
export var vextend = extend

tsconfig.json

{
  "compilerOptions": {
    "checkJs": true,
    "allowJs": true
  }
}

VSCode error

Error processing request. Cannot set property 'typeParameters' of undefined
TypeError: Cannot set property 'typeParameters' of undefined
    at assignContextualParameterTypes (/project/node_modules/typescript/lib/tsserver.js:36049:38)
    at checkFunctionExpressionOrObjectLiteralMethod (/project/node_modules/typescript/lib/tsserver.js:36336:29)
    at checkObjectLiteralMethod (/project/node_modules/typescript/lib/tsserver.js:37103:38)
    at checkObjectLiteral (/project/node_modules/typescript/lib/tsserver.js:33798:32)
    at checkExpressionWorker (/project/node_modules/typescript/lib/tsserver.js:37192:28)
    at checkExpression (/project/node_modules/typescript/lib/tsserver.js:37144:42)
    at checkExpressionForMutableLocation (/project/node_modules/typescript/lib/tsserver.js:37088:24)
    at checkPropertyAssignment (/project/node_modules/typescript/lib/tsserver.js:37096:20)
    at checkObjectLiteral (/project/node_modules/typescript/lib/tsserver.js:33795:32)
    at checkExpressionWorker (/project/node_modules/typescript/lib/tsserver.js:37192:28)
    at checkExpression (/project/node_modules/typescript/lib/tsserver.js:37144:42)
    at checkExpressionWithContextualType (/project/node_modules/typescript/lib/tsserver.js:37034:26)
    at checkApplicableSignature (/project/node_modules/typescript/lib/tsserver.js:35155:25)
    at chooseOverload (/project/node_modules/typescript/lib/tsserver.js:35460:26)
    at resolveCall (/project/node_modules/typescript/lib/tsserver.js:35380:26)
    at resolveCallExpression (/project/node_modules/typescript/lib/tsserver.js:35567:20)
    at resolveSignature (/project/node_modules/typescript/lib/tsserver.js:35762:28)
    at getResolvedSignature (/project/node_modules/typescript/lib/tsserver.js:35782:26)
    at Object.getResolvedSignature (/project/node_modules/typescript/lib/tsserver.js:21856:34)
    at Object.getSymbolDisplayPartsDocumentationAndSymbolKind (/project/node_modules/typescript/lib/tsserver.js:75554:45)
    at Object.getQuickInfoAtPosition (/project/node_modules/typescript/lib/tsserver.js:84632:39)
    at IOSession.Session.getQuickInfoWorker (/project/node_modules/typescript/lib/tsserver.js:91480:62)
    at Session.handlers.ts.createMapFromTemplate._a.(anonymous function) (/project/node_modules/typescript/lib/tsserver.js:90597:61)
    at /project/node_modules/typescript/lib/tsserver.js:92067:88
    at IOSession.Session.executeWithRequestId (/project/node_modules/typescript/lib/tsserver.js:92058:28)
    at IOSession.Session.executeCommand (/project/node_modules/typescript/lib/tsserver.js:92067:33)
    at IOSession.Session.onMessage (/project/node_modules/typescript/lib/tsserver.js:92087:35)
    at Interface.<anonymous> (/project/node_modules/typescript/lib/tsserver.js:93288:27)
    at emitOne (events.js:96:13)
    at Interface.emit (events.js:191:7)
    at Interface._onLine (readline.js:241:10)
    at Interface._normalWrite (readline.js:384:12)
    at Socket.ondata (readline.js:101:10)
    at emitOne (events.js:96:13)
    at Socket.emit (events.js:191:7)
    at readableAddChunk (_stream_readable.js:178:18)
    at Socket.Readable.push (_stream_readable.js:136:10)
    at Pipe.onread (net.js:560:20)