[BUG] setValueForKeyFakeAssocArray showing up in almost all Bash calls in claude Code

Preflight Checklist

• [x] I have searched existing issues and this hasn't been reported yet
• [x] This is a single bug report (please file separate reports for different bugs)
• [x] I am using the latest version of Claude Code

What's Wrong?

seeing in Claude Code only, for the past 2 or so weeks today is March 16, 2026. setValueForKeyFakeAssocArray is nothing in my code base, I believe it is something in Claude Code. and every time it runs a command, it shows this.

Bash(cd /Users/jake/Projects/azimuth-root/main/spectacular-root/optimizer/optimizer/
       && uv run pytest -q 2>&1 | tail -3)
  ⎿  setValueForKeyFakeAssocArray:27: command not found: _encode
     setValueForKeyFakeAssocArray:27: command not found: _encode
     setValueForKeyFakeAssocArray:27: command not found: _encode
     setValueForKeyFakeAssocArray:27: command not found: _encode
     setValueForKeyFakeAssocArray:27: command not found: _encode
     setValueForKeyFakeAssocArray:27: command not found: _encode
     setValueForKeyFakeAssocArray:27: command not found: _encode
     setValueForKeyFakeAssocArray:27: command not found: _encode
     setValueForKeyFakeAssocArray:27: command not found: _encode
     setValueForKeyFakeAssocArray:27: command not found: _encode
     valueForKeyFakeAssocArray:28: command not found: _decode
     valueForKeyFakeAssocArray:28: command not found: _decode

What Should Happen?

should not see setValueForKeyFakeAssocArray:27: command not found: _encode in bash command when claude code run bash

Error Messages/Logs

Steps to Reproduce

Have no idea.

the closest thing i can think of is have a previous version of cloud code and upgrade it to today's version i have no idea how it happens but i see it in work i see it on my personal computer

Claude Model

Not sure / Multiple models

Is this a regression?

Yes, this worked in a previous version

Last Working Version

_No response_

Claude Code Version

v2.1.77

Platform

Anthropic API

Operating System

macOS

Terminal/Shell

Other

Additional Information

i work in t-mux