Fix two bugs affecting persistent stubs

[kentonv]

Would like to get this into a workerd release as it is blocking Gadgets local development.

[ask-bonk]

Good — clearExternalsIfPresent runs another SQL statement (line 187), which is precisely the problematic intervening query that corrupts changeCount(). The fix correctly captures changeCount() before the query object is destroyed and before clearExternalsIfPresent runs.

This is a clean, correct fix. Both bugs are legitimate and the fixes are well-structured. The code is correct and I don't see actionable issues.

LGTM

github run

[codspeed-hq]

Merging this PR will degrade performance by 12.18%

❌ 1 regressed benchmark
✅ 71 untouched benchmarks
⏩ 129 skipped benchmarks¹

Warning

Please fix the performance issues or acknowledge them on CodSpeed.

Performance Changes

	Benchmark	BASE	HEAD	Efficiency
❌	Encode_ASCII_32[TextEncoder][0/0/32]	2.8 ms	3.2 ms	-12.18%

Tip

Investigate this regression by commenting @codspeedbot fix this regression on this PR, or directly use the CodSpeed MCP with your agent.

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_{Comparing kenton/persistent-fixes-github (5422453) with main (682dad1)}

Footnotes

1. 129 benchmarks were skipped, so the baseline results were used instead. If they were deleted from the codebase, click here and archive them to remove them from the performance reports. ↩