[DataGrid] Fix bug in suspense

[romgrk]

Close #12459

Avoid using a ref that may be undefined.

Before: https://codesandbox.io/p/sandbox/mui-x-datagrid-issue-12459-tl2vy4
After: https://codesandbox.io/p/sandbox/mui-mui-x-x-data-grid-forked-q5lln4

[mui-bot]

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[scamden]

will this fix only apply to v7 or will you be backporting to v6?

(we have run into the issue this seems to fix and a few other suspense bugs with DataGrid and I'm wondering whether v7 would have more fixes for Suspense in general, but the migration is time consuming)

[cherniavskii]

@scamden This fix was not backported to v6.

a few other suspense bugs with DataGrid

Can you open a new issue with a reproduction example?
I can cherry-pick some fixes to v6 if necessary.

[scamden]

this was the other big one that causes a few different symptom issues: #6879 (comment)

The apiRef becomes null during suspense which then can throw if MUI calls certain callbacks or events during that time. I mentioned one in the comment, but i think high level the root cause is nulling the ref out during suspense (which MUI throws a warning about even when there's no error). UPDATE: got a repro for you finally: #6879 (comment)

I can cherry-pick some fixes to v6 if necessary.

Thank you! This particular fix would be great.

The apiRef being null issue doesn't seem to have a fix yet and was dismissed as just a warning, but it does in fact cause errors (we have null checking throughout our code now to tell TS the ref can be null, which works for our code but seems silly)