Launcher crashes when `REME_PATH`/`REME_SCRIPT` are unset

[arjuntheprogrammer]

Description

Running python launcher.py --conf examples/overall.yaml --with-appworld --with-reme fails when ReMe-specific environment variables are not defined. load_dotenv only populates values that exist in a .env file, so in a fresh clone the required REME_PATH and REME_SCRIPT entries remain None. The launcher passes these values straight into LaunchCommandWhenAbsent, which attempts to hash them and crashes before ReMe is started.

Steps to Reproduce

1. Clone modelscope/AgentEvolver (commit 2d7c14a2).
2. Ensure no .env file provides ReMe variables (default state).
3. conda activate agentevolver.
4. Run python launcher.py --conf examples/overall.yaml --with-appworld --with-reme.

Expected Result

Launcher either starts ReMe or reports that the ReMe service configuration is missing in a user-friendly way.

Actual Result

Launcher aborts with a TypeError while computing the companion process hash because service_script is None:

Traceback (most recent call last):
  File "launcher.py", line 396, in <module>
    main()
  File "launcher.py", line 328, in main
    pty_launch("reme", success_std_string="Uvicorn running on")
  File "launcher.py", line 104, in pty_launch
    companion = LaunchCommandWhenAbsent(
  File "agentevolver/utils/daemon.py", line 276, in __init__
    self.script_hash = hashlib.md5(''.join(hash_items).encode()).hexdigest()[:8]
TypeError: sequence item 0: expected str instance, NoneType found

Environment

• OS: Ubuntu 22.04.5 LTS
• Python: conda env agentevolver
• Commit: 2d7c14a2

Suggested Fix

Validate that REME_PATH and REME_SCRIPT are set before invoking LaunchCommandWhenAbsent, and emit a clear error (or provide defaults) instead of proceeding with None values.