Fix #11427: Wrong "dead catch" error, side effects of ArrayAccess not considered

[phpstan-bot]

Summary

When using array syntax on ArrayAccess objects, PHP implicitly calls offsetGet, offsetExists, offsetUnset, or offsetSet. These methods can throw exceptions, but only offsetSet (array assignment) was generating throw points in the analysis. This caused false "dead catch" errors when catching exceptions from isset($x[1]), $x[1] reads, and unset($x[1]) on ArrayAccess implementations.

Changes

• src/Analyser/NodeScopeResolver.php: Added synthetic MethodCall throw point collection for:
  • offsetGet in the ArrayDimFetch expression handler (reading $x[1])
  • offsetUnset in the Unset_ statement handler (for unset($x[1]))
  • offsetExists in the Isset_ expression handler (for isset($x[1]))
• tests/PHPStan/Rules/Exceptions/data/bug-11427.php: Regression test with ArrayAccess class whose methods throw
• tests/PHPStan/Rules/Exceptions/CatchWithUnthrownExceptionRuleTest.php: Added testBug11427 method
• CLAUDE.md: Documented the ArrayAccess throw point synthesis pattern

Root cause

NodeScopeResolver already synthesized a MethodCall to offsetSet when processing array assignments on ArrayAccess objects (line ~6291), which properly generated throw points for dead-catch analysis. However, the same pattern was missing for the other three ArrayAccess operations: offsetGet (array read), offsetUnset (unset), and offsetExists (isset). Without these synthetic method calls, their potential exceptions were invisible to the dead-catch rule.

Test

The regression test creates an ArrayAccess class where all four offset methods throw \Exception, then wraps each operation in try/catch blocks. Before the fix, 3 of 4 catch blocks were incorrectly reported as dead catches. After the fix, no errors are reported.

Fixes phpstan/phpstan#11427