Unexpected value xxx imported by the module xxx Please add a @NgModule annotation

问题

I'm attempting to convert an existing Angular app from 5.2.5 to 6.0.8. After some time struggling with an error, I've created a relatively straightforward repro which can be found here:

https://github.com/DelphiWorlds/Angular6Issue

The error on my machine comes out as:

ERROR in : Unexpected value 'TestModule in C:/Source/angular6issue/test/app/node_modules/test-package-a6/dist/index.d.ts' imported by the module 'AppModule in C:/Source/angular6issue/test/app/src/app/app.module.ts'. Please add a @NgModule annotation.

Edit: Note that it's just building for production that I'm having an issue with - it builds and runs fine in dev mode

来源：https://stackoverflow.com/questions/51147293/unexpected-value-xxx-imported-by-the-module-xxx-please-add-a-ngmodule-annotatio