### Version 3.0.0-rc.3 ### Reproduction link [https://github.com/bobmoff/vue-cli-not-a-module](https://github.com/bobmoff/vue-cli-not-a-module) ### Steps to reproduce yarn build ### What is expected? Successful compilation ### What is actually happening? ERROR in /Users/smk17/VsCode/hello-world/src/main.ts 3:17 File '/Users/smk17/VsCode/hello-world/src/App.vue' is not a module. --- I extracted ts to `App.ts` in `App.vue` and introduced it in the following way: <script src="./App.ts"></script> <!-- generated by vue-issues. DO NOT REMOVE -->