Fix three snapshots bugs

[andrewbranch]

• Fixes an issue with ATA caching that could cause a "No project found for file" error message when opening JS files in inferred projects
• Fixes a crash when a tsconfig.json "extends" target doesn't exist
• Fixes LSP - invalid memory address or nil pointer dereference - findOrCreateDefaultConfiguredProjectWorker #1630 (pretty sure)

[sheetalkamat]

Looks good but fix the errors in tests ?

[Copilot]

Pull Request Overview

This PR fixes two snapshot-related bugs in the TypeScript compiler port: an ATA caching issue that caused "No project found for file" errors when opening JS files in inferred projects, and a crash when a tsconfig.json extends a non-existent target.

• Adds null safety checks for extended config handling to prevent crashes when config files don't exist
• Fixes ATA cache invalidation by resetting commandLineWithTypingsFiles when command line changes
• Adds comprehensive test coverage for both bug scenarios

Reviewed Changes

Copilot reviewed 6 out of 6 changed files in this pull request and generated no comments.

Show a summary per file

File	Description
internal/tsoptions/tsconfigparsing.go	Adds null safety check for extended config result handling
internal/project/projectcollectionbuilder.go	Adds early returns for missing configs/projects and resets cached typing files
internal/project/extendedconfigcache.go	Adds null safety for file handle hash calculation
internal/project/projectcollectionbuilder_test.go	Adds test for config file registry cleanup scenario
internal/project/project_test.go	Adds test for ATA cache invalidation bug
internal/project/configfilechanges_test.go	Adds test for missing extended config creation scenario