"Cannot convert undefined or null to object" when ng serve with fesm15 files

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Current behavior Exception thrown in the browser (during metadata collection?) in JIT mode:

Unhandled Promise rejection: Cannot convert undefined or null to object ; Zone: <root> ; Task: Promise.then ; Value: TypeError: Cannot convert undefined or null to object
    at Function.getPrototypeOf (<anonymous>)
    at getParentCtor (reflection_capabilities.ts:324)
    at ReflectionCapabilities.parameters (reflection_capabilities.ts:115)
    at Reflector.parameters (reflector.ts:42)
    at CompileMetadataResolver._getDependenciesMetadata (metadata_resolver.js:794)
    at CompileMetadataResolver._getFactoryMetadata (metadata_resolver.js:729)
    at CompileMetadataResolver.getProviderMetadata (metadata_resolver.js:1001)
    at JitCompiler._compileModule (compiler.js:172)
    at createResult (compiler.js:116)
    at ZoneDelegate.invoke (zone.js:334)
    at Zone.run (zone.js:126)
    at zone.js:713
    at ZoneDelegate.invokeTask (zone.js:367)
    at Zone.runTask (zone.js:166)
    at drainMicroTaskQueue (zone.js:546) TypeError: Cannot convert undefined or null to object
    at Function.getPrototypeOf (<anonymous>)
    at getParentCtor (http://localhost:4200/vendor.bundle.js:2414:49)
    at ReflectionCapabilities.parameters (http://localhost:4200/vendor.bundle.js:2234:45)
    at Reflector.parameters (http://localhost:4200/vendor.bundle.js:2496:44)
    at CompileMetadataResolver._getDependenciesMetadata (http://localhost:4200/vendor.bundle.js:40117:73)
    at CompileMetadataResolver._getFactoryMetadata (http://localhost:4200/vendor.bundle.js:40056:51)
    at CompileMetadataResolver.getProviderMetadata (http://localhost:4200/vendor.bundle.js:40324:43)
    at JitCompiler._compileModule (http://localhost:4200/vendor.bundle.js:50248:77)
    at createResult (http://localhost:4200/vendor.bundle.js:50192:25)
    at ZoneDelegate.invoke (http://localhost:4200/polyfills.bundle.js:2970:26)
    at Zone.run (http://localhost:4200/polyfills.bundle.js:2762:43)
    at http://localhost:4200/polyfills.bundle.js:3349:57
    at ZoneDelegate.invokeTask (http://localhost:4200/polyfills.bundle.js:3003:31)
    at Zone.runTask (http://localhost:4200/polyfills.bundle.js:2802:47)
    at drainMicroTaskQueue (http://localhost:4200/polyfills.bundle.js:3182:35)

Expected behavior No error

Minimal reproduction of the problem with instructions

1. ng new --ng4 test-app
2. edit vi node_modules/\@angular/cli//models/webpack-configs/common.js and mainFields: ["es2015", "module", "main"] to resolve: { ... } block
3. ng serve
4. open http://localhost:4200 and check error in console

• Angular version: 4.0.0-rc.5

[jusefb]

I have just done a simple upgrade from Angular 2 to Angular 4 and can not use the app anymore due to this error. Can anyone suggest a workaround? Please ignore, I have found the offending module. It was down to ngrx/store-devtools. Once I have upgraded to the latest version of this problem the issue went away

[tbosch]

This is because in native ES6, arrow functions don’t have a prototype field, which fails our metadata collection. E.g. the following test is different between ES6 and transpiled ES5 code:

const x = () => null;
expect(x.prototype).toBeDefined()

But if this error would not throw, we would see the error described in #14816.

Closing in favor of the tracking bug #15127