Fix crash in abstract property checking

[ahejlsberg]

Fixes #62920.

[Copilot]

Pull request overview

This PR fixes a crash (issue #62920) that occurred when TypeScript tried to report an error about accessing an abstract property in the constructor of an unnamed class expression. The crash happened because the code attempted to access the name property of an unnamed class declaration, which is undefined for class expressions without explicit names.

Key Changes

• Modified the abstract property accessibility check to avoid dereferencing potentially undefined values
• Changed error message generation to use symbolToString() instead of accessing the class declaration's name property directly
• Added a test case demonstrating the crash scenario with appropriate baselines

Reviewed changes

Copilot reviewed 5 out of 5 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
src/compiler/checker.ts	Fixed crash by checking parent symbol validity and using symbolToString() instead of accessing declaration name
tests/cases/compiler/errorInUnnamedClassExpression.ts	Added test case with unnamed class expression containing abstract property accessed in constructor
tests/baselines/reference/errorInUnnamedClassExpression.types	Baseline for type information
tests/baselines/reference/errorInUnnamedClassExpression.symbols	Baseline for symbol information
tests/baselines/reference/errorInUnnamedClassExpression.errors.txt	Baseline showing correct error messages (TS2715, TS1253, TS7008)

[Copilot]

Missing spaces around the bitwise AND operator. The pattern should be parentSymbol.flags & SymbolFlags.Class with spaces on both sides of the & operator to match the codebase style.

[ahejlsberg]

This was ported to typescript-go in microsoft/typescript-go#2423.