Describe the bug
When placing foo/index.htm into public folder, build command produces an error.
In development, this works fine – /foo/ correctly served as HTML

When running build, I get
Unexpected token (Note that you need plugins to import files that are not JavaScript)

Changing file estension from .htm to .html fixes the problem.

To Reproduce
Steps to reproduce the behavior:

1. Go to /public
2. Add a folder 'foo' and put index.htm into it with some html inside
3. Run npm run start and navigate to /foo/ in browser
4. Run npm run build and see error:
   Unexpected token (Note that you need plugins to import files that are not JavaScript)

Expected behavior
I’d expect .htm to behave the same way as .html. Build successfully copies foo/index.html into dist

Desktop (please complete the following information):

• OS: macOS 10.14.6
• Browser: Firefox, Brave
• WMR Version 1.3.2

Additional context
Not a huge deal, but showing an error about htm not being supported might save time for someone.