fix(core): retry lazy initializer after it throws - #39597
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lazy() marked itself loaded before invoking fn(), so a throwing initializer left loaded=true with value unset. Every later call then hit the memoized fast path and returned undefined, hiding the real error and making a transient failure permanent. Only memoize after fn() returns.
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The following comment was made by an LLM, it may be inaccurate: The second result (PR #12520) is unrelated—it's about an MCP search tool, not the lazy() utility function. No duplicate PRs found |
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Thanks for updating your PR! It now meets our contributing guidelines. 👍 |
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Issue for this PR
Closes #39596
Type of change
What does this PR do?
lazy()setloaded = truebefore callingfn(). If the initializer throws,loadedis already true butvaluewas never assigned, so every later call takes theif (loaded)fast path and returnsundefinedforever. The real error is swallowed and a transient failure becomes permanent.Moving the assignment after
fn()returns fixes it: a throw now leavesloadedfalse, so the next call retries. Success path is unchanged - still onefn()call, still caches anundefinedresult.How did you verify your code works?
Added
packages/core/test/util/lazy.test.ts(4 tests: caching, retry after throw, repeated failure, cachedundefined).Checked the tests actually catch the bug - reverted the src change and the two retry tests fail (
Received function did not throw, receivedundefined); with the fix 4/4 pass.bun typecheckclean inpackages/core;bun test test/util/31/31 pass.Screenshots / recordings
Not a UI change.
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