import type doesn't show error from file with no flow pragma

I hope it's not duplicated I couldn't find any similar issue.
If file `a.js` import type from `b.js` and `b.js` doesn't have a flow pragma it doesn't report any error. I would suggest it will report error. Since:
1. You shouldn't import type from a file which has no flow pragma
2. But even more important, To discover when `import type` had happened with a file which has a typo in the pragma of `@flow`