Fix flask backend mimetype for modules

[elro444]

_{By submitting this pull request you agree that all contributions to this project are made under the MIT license.}

Issues

When running reactpy with Flask backend, web.module_from_template resulted an error (in the browser) about wrong mimetype. In example:

Failed to load module script: Expected a JavaScript module script but the server responded with a MIME type of "application/octet-stream". Strict MIME type checking is enforced for module scripts per HTML spec.
Uncaught (in promise) TypeError: Failed to fetch dynamically imported module: http://localhost:8000/_reactpy/modules/__from_template__/@material-ui/core@4.12.4.4.js

Solution

Explicitly add the mimetype when using send_file

Checklist

• Tests have been included for all bug fixes or added functionality.
• The changelog.rst has been updated with any significant changes.

[rmorshea]

I think we can do this, but is this possibly related to this sort of issue?

[elro444]

Possibly, but doesn't seem to be exactly the same.
In any case, I just lookd at reactpy's implementation for the sanic backend, and saw that we do indeed pass there the text/javascript mimetype.

[elro444]

Umm, seems like the lint checks are broken?
Is it supposed to fail on files that i havened modified?

[rmorshea]

No. I'll put up a fix for that shortly.

[elro444]

Hey @rmorshea any updates on this issue?