[StyledEngineProvider] Fix issue with cache not being defined

[mnajdova]

Fixes #36096, a regression from #36001. The emotion cache provided previously could have been undefined, which was throwing an error. The changes were tested locally, the codesandboxes takes ages to load for me 😕

Before: https://codesandbox.io/s/lucid-dan-n6hu29?file=/package.json
After: https://codesandbox.io/s/pensive-violet-on5wym?file=/package.json

[mui-bot]

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[siriwatknp]

I guess we could write a test for this? Is it possible to remove document at the beginning of the test?

[mnajdova]

I guess we could write a test for this? Is it possible to remove document at the beginning of the test?

The problem with removing the document is that the render from createRenderer no longer works, we will need some kind of a server side rendering util, which I don't think the react-testing-library provides, based on testing-library/react-testing-library#561

[m4theushw]

If you like we could also revert this change and improve the check I added in #36001. For mui/mui-x#7770, I only need to prevent creating the cache if MUI Core is being used inside a web worker. My first idea was to check the presence of document because the error message mentioned this, but checking if importScript is available (there're other approaches too) might be more reliable to avoid false-positives.

[mnajdova]

If you like we could also revert this change and improve the check I added in #36001. For mui/mui-x#7770, I only need to prevent creating the cache if MUI Core is being used inside a web worker. My first idea was to check the presence of document because the error message mentioned this, but checking if importScript is available (there're other approaches too) might be more reliable to avoid false-positives.

@m4theushw can this be conditionally added on MUI X side (for example using StyledEngineProvider only when it makes sense)? In my opinion most of the people would anyway need a custom cache, but seems like it broke quite a lot of people, so maybe it's worth adding the check in MUI Core, for similar scenarios.

[m4theushw]

can this be conditionally added on MUI X side (for example using StyledEngineProvider only when it makes sense)?

No, we actually don't even use StyledEngineProvider in the web worker. The problem is that as soon as MUI Core is imported the cache is created.