fix(tools): Resolve intermittent hangs and lack of clear error feedback in apply_diff tool

[lhish]

Related GitHub Issue

Closes: #5390

Description

This PR addresses an issue where the apply_diff tool (specifically within the multiApplyDiffTool) would intermittently hang when encountering an error during file modification. The root cause was improper error handling; exceptions thrown during XML parsing or diff application were not being caught and propagated correctly. This caused the tool's execution to stall indefinitely without providing any feedback to the user interface, which in turn could confuse the LLM and lead to repetitive, incorrect outputs.

I have changed the original silent error into an explicit editing error that is now displayed in the UI and reported back to the LLM.

Test Procedure

I tested this fix using several real-world cases where I previously encountered this issue, and it resolved the problem successfully in all of them. I attempted to write a new test, but I was unable to determine the specific type of malformed XML that would cause the parser to fail in this exact way, which made it impossible to create a reproducible test case.

Pre-Submission Checklist

• Issue Linked: This PR is linked to an approved GitHub Issue (see "Related GitHub Issue" above).
• Scope: My changes are focused on the linked issue (one major feature/fix per PR).
• Self-Review: I have performed a thorough self-review of my code.
• Testing: New and/or updated tests have been added to cover my changes (if applicable).
• Documentation Impact: I have considered if my changes require documentation updates (see "Documentation Updates" section below).
• Contribution Guidelines: I have read and agree to the Contributor Guidelines.

Documentation Updates

• No documentation updates are required.

This is a bug fix that improves the stability and error-reporting behavior of an existing tool. It does not change the tool's functionality from a user's perspective, so no documentation updates are needed.

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Important

Fixes intermittent hanging in applyDiffTool by improving error handling and feedback in multiApplyDiffTool.ts.

• Behavior:
  • Fixes intermittent hanging issue in applyDiffTool in multiApplyDiffTool.ts by improving error handling.
  • Converts silent errors during XML parsing and diff application into explicit errors reported to the UI and LLM.
• Error Handling:
  • In applyDiffTool, catches exceptions during XML parsing and diff application, increments cline.consecutiveMistakeCount, records tool error, and reports detailed error message.
  • Uses cline.say to communicate errors and pushToolResult to log them.
• Misc:
  • Closes issue Bug: apply_diff tool intermittently hangs and lacks clear error feedback #5390.

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[daniel-lxs]

Thank you @lhish!

I made a small change to properly show the error to the user, but everything looks good!