Bug: error.msg should be error.message in write-file handler catch block

[dsurchisactive]

Description

The error catch block in the write_file tool handler accesses error.msg instead of error.message, causing all non-string error details to be lost.

Root Cause

In packages/agent-runtime/src/tools/handlers/tool/write-file.ts (line 142):

.catch((error) => {
  // ...
  return {
    tool: 'write_file' as const,
    path,
    error: `Error: Failed to process the write_file block. ${typeof error === 'string' ? error : error.msg}`,
  }
})

Standard JavaScript Error objects have a .message property, not .msg. When processFileBlock() throws a non-string error (which is the common case), error.msg evaluates to undefined, and the error message becomes:

Error: Failed to process the write_file block. undefined

This is the only occurrence of .msg in the codebase — all other error handling correctly uses .message.

Impact

When a file write operation fails with a non-string error, the actual error details are lost. Users and logs see "undefined" instead of the real error message, making debugging difficult.

Suggested Fix

error: `Error: Failed to process the write_file block. ${typeof error === 'string' ? error : error.message}`,