Prevent infinite loop in unstable AST JSDoc scanner

[Copilot]

The unstable AST JSDoc scanner could loop indefinitely when a scan range ended immediately after -, because the range check did not guard the full identifier condition.

Changes

• Guard both identifier parts and hyphens with pos < end:

while (pos < end && (isIdentifierPart(...) || char === CharacterCodes.minus))

• Add regression coverage verifying that a range ending in x- reaches EOF and preserves the expected tokens.

• Fixes unstable/ast: scanJsDocToken infinite-loops when a scan range ends on a trailing '-' (fix from #63581 not carried into the AST scanner) #64135

[Copilot]

🟢 Approval recommended

The focused fix correctly addresses the precedence bug and includes matching regression coverage.

Pull request overview

Fixes an infinite loop in the unstable AST JSDoc scanner when a scan range ends with a hyphen.

Changes:

• Correctly bounds hyphenated identifier scanning.
• Adds regression coverage for EOF and token preservation.

File summaries

File	Description
packages/typescript/src/ast/scanner.ts	Fixes the scanner range condition.
packages/typescript/test/scanner.test.ts	Tests trailing-hyphen range scanning.

Review details

• Files reviewed: 2/2 changed files
• Comments generated: 0
• Review effort level: Balanced

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