fix(sentinel-graph): preserve narrowed token type for mypy 1.14

Return the locally-bound token (typed 'str') instead of cfg._token
(typed 'Optional[str]'). Functionally equivalent — token is assigned
to cfg._token on the previous line — but mypy 1.14 (the pinned mypy
on the Python 3.8 lockfile) does not narrow the field-access form and
flagged: 'Incompatible return value type (got str | None, expected str)'.

mypy 1.20+ (3.10+ lockfiles) accepted the original code, which is why
the failure was 3.8-specific. Verified clean with both mypy 1.14 and
1.20.2; sentinel-graph tests still pass.

Author: SinsBre

graphistry/plugins/sentinel_graph.py

@@ -378,11 +378,12 @@ def _get_auth_token(self) -> str:
 
             # Get token
             token_obj = credential.get_token(cfg.auth_scope)
-            cfg._token = token_obj.token
+            token = token_obj.token
+            cfg._token = token
             cfg._token_expiry = token_obj.expires_on
 
             logger.info("Successfully obtained authentication token")
-            return cfg._token
+            return token
 
         except Exception:
             # Security: Don't expose credential details or exception messages