The Profiler stores:
1. A snapshot of the React tree when profiling started
2. The operations array for each commit
3. Profiling metadata (e.g. durations, what changed, etc) for each commit
It uses this information (snapshot + operations diff) to reconstruct the state of the application for a given commit as it's viewed in the Profiler UI. Because of this, it's very important that the operations and metadata arrays align. If they don't align, the profiler will be unable to correctly reconstruct the tree, and it will likely throw errors (like 'Could not find node…')
#16446 tracks a long-standing bug where these two arrays get misaligned. I am still not entirely sure what causes this bug, but with PR #17253, I exacerbated things by introducing another potential way for it to happen. This PR addresses the regression at least (and adds test coverage for it).
I will follow up this afternoon on the original #16446 issue. I think I may have a lead on what's happening at least, if not exactly an idea of how to reproduce it.
