Fix binding element phantom error

[ahejlsberg]

Removes an incorrect reuse of cached types for binding element parents as suggested here.

Fixes #3276.

[Copilot]

Pull request overview

This PR fixes an intermittent type-checking error involving optional destructuring parameters by tightening when the checker reuses cached resolvedType values for binding element parents (avoiding reuse when the cached type may have included optionality).

Changes:

• Adjust getTypeForBindingElementParent to avoid reusing valueSymbolLinks.resolvedType for optional declarations under strictNullChecks.
• Add a compiler repro test covering the previously intermittent phantom error scenario.
• Add/update reference .types and .symbols baselines for the new test.

Reviewed changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated no comments.

File	Description
internal/checker/checker.go	Prevents reuse of cached parent types for binding patterns when optionality could be baked into the cached type, fixing the phantom error.
testdata/tests/cases/compiler/bindingPatternOptionalParameterCached.ts	Adds a minimal repro that should typecheck without errors (regression test for #3276).
testdata/baselines/reference/compiler/bindingPatternOptionalParameterCached.types	Records expected type baseline output for the new test.
testdata/baselines/reference/compiler/bindingPatternOptionalParameterCached.symbols	Records expected symbol baseline output for the new test.