fix: correctly check for promise in useLoadData

[NielsJPeschel]

Proposed changes

Currently, useLoadData makes the assumption a promise is a native promises. Non-native promises lead to a bug where we immediately assign loadedData.result a promise without ever evaluating that promise.

The fix is to go into further depth when checking initial promise.

Types of changes

What types of changes does your code introduce?
Put an x in the boxes that apply

• Bugfix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)

Checklist

Put an x in the boxes that apply. You can also fill these out after creating the PR. If you're unsure about any of them, don't hesitate to ask. We're here to help! This is simply a reminder of what we are going to look for before merging your code.

• I have read the CONTRIBUTING doc
• I have added tests that prove my fix is effective or that my feature works
• I have added necessary documentation (if appropriate)
• Any dependent changes have been merged and published in downstream modules

Further comments

[NielsJPeschel]

@nthurow Ran this test with how useLoadData was written before (ie using instanceof Promise), and it did in fact fail! I was worried we wouldn't be able to test this scenario adequately, but glad that isn't the case!

[NielsJPeschel]

we should start looking at automating this