Unhandled Promise rejection when invoking custom slash command

Bug Description

When attempting to invoke a custom slash command, Claude Code throws an unhandled Promise rejection error before the command executes.

Steps to Reproduce

1. Create a custom command in .claude/commands/
2. Attempt to invoke it using /command-name
3. Error is thrown

Error Message

This error originated either by throwing inside of an async function without a catch block, or by rejecting a promise which was not handled with .catch(). The promise rejected with the reason:
Error
    at <anonymous> (/$bunfs/root/claude:2764:25947)
    at map (unknown:1:11)
    at RPA (/$bunfs/root/claude:2764:25833)
    at <anonymous> (/$bunfs/root/claude:2767:6928)
    at <anonymous> (/$bunfs/root/claude:2767:7587)
    at <anonymous> (/$bunfs/root/claude:2767:7628)
    at oA (/$bunfs/root/claude:678:62377)
    at Qq (/$bunfs/root/claude:678:75291)
    at I4 (/$bunfs/root/claude:678:75175)
    at Qq (/$bunfs/root/claude:678:76074)

Environment

• OS: Linux (WSL2) 6.6.87.1-microsoft-standard-WSL2
• Claude Code Version: 2.1.6

Additional Context

The error occurs during command parsing/loading phase, not during command execution.