Heisenbug

Definitions

1. A bug that disappears or changes behavior when you try to observe or debug it — named after Heisenberg's uncertainty principle. Common causes: race conditions (adding logging changes timing), uninitialized memory (debugger zeros it), and compiler optimizations (debug builds behave differently). The most frustrating class of bugs.

   In plain English: A bug that vanishes when you try to debug it, like a ghost that only appears when you're not looking.

   Example: "The crash only happens in production — adding console.log makes it disappear. Classic Heisenbug, probably a race condition."

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