fix: ESM compatibility

[ffMathy]

Supersedes ftrackhq/ftrack-javascript#199

• I have added automatic tests where applicable
• The PR title is suitable as a release note
• The PR contains a description of what has been changed
• The description contains manual test instructions

Changes

Test

[ffMathy]

CC @jimmycallin.

[jimmycallin]

When you tested this by changing this locally, did you rename the outputted file to .mjs as well or just updated the package.json?

[ffMathy]

I renamed the file as well. I also just now tried renaming it back, and then it doesn't work. So it is indeed needed.

[jimmycallin]

I'm a bit confused why this is needed for @ftrack/web-widget and not @ftrack/api so wonder if there is another underlying issue with the config that renaming to mjs hides. Will try to have a closer look later today.

[ffMathy]

I mean, either way it's good practice to use the mjs format, and I can't see a scenario where it breaks anything.

Let me know what you find either way. It's very interesting.

[jimmycallin]

@ffMathy the issue is actually a missing property "type": "module" in package.json, mind updating your pr and verifying that it works?

[ffMathy]

Well, now we are switching away from Jest as well and to Vitest, just like you 😆 I think we got inspired.

The VS Code Extension for Jest is a bit annoying.

So I won't have time to check this out anymore unfortunately.

[jimmycallin]

Good choice :) I'll go ahead and close this PR and apply the fixes separately