Bug: Uncaught NameError crash when X-OAuth-Scopes header is missing during GitHub token validation

[SunkariManwithaGopal]

Summary

The GitHub MCP Agent crashes with an unhandled NameError in the manual token verification flow when the X-OAuth-Scopes response header is missing. The variable scopes is only conditionally initialized, but is later referenced unconditionally in the check:
if 'repo' not in scopes:
If the header is absent (common with invalid tokens, fine-grained tokens, or some API responses), the handler throws:
NameError: name 'scopes' is not defined
This causes the chat message handler to terminate unexpectedly, resulting in a denial-of-service condition for the affected session.

Steps to reproduce

1.Start the GitHub MCP Agent:

python agent.py

2. Send a message containing an invalid or unsupported GitHub token:

ghp_invalidtokenfortesting

3.The agent attempts token validation and requests:

GET /user

If the response does not contain the X-OAuth-Scopes header, the variable scopes is never initialized.

4.Observe the crash when execution reaches:

if 'repo' not in scopes:

#133

Expected behavior

The agent should gracefully handle missing X-OAuth-Scopes headers by initializing scopes to a safe default value (e.g. empty string or empty list) and returning a clean validation error message instead of crashing.

Actual behavior

The message handler crashes with an unhandled exception:

NameError: name 'scopes' is not defined

This terminates the current request/session flow and prevents graceful error handling.

Affected file or folder path

mcp-agents/Github MCP Agent/agent.py

Logs / traceback

Traceback (most recent call last):
  File "agent.py", line XXX, in handle_chat_message
    if 'repo' not in scopes:
NameError: name 'scopes' is not defined

Environment

OS: macOS / Linux Python: 3.11 Affected Component: GitHub MCP Agent