detect 'refresh to login' failures earlier to throw a better error.

Author: carl-adams-planet

src/planet_auth/oidc/request_authenticator.py

@@ -17,6 +17,7 @@
 from typing import Dict, Optional
 
 import planet_auth.logging.auth_logger
+from planet_auth import AuthException
 from planet_auth.credential import Credential
 from planet_auth.request_authenticator import CredentialRequestAuthenticator
 from planet_auth.oidc.auth_client import OidcAuthClient
@@ -123,6 +124,11 @@ def _refresh_if_needed(self):
                     msg="Error refreshing auth token. Continuing with old auth token. Refresh error: " + str(e)
                 )
 
+        if not (self._credential and self._credential.is_loaded()):
+            # "refresh" may also be called to initialize in some cases, as in client credentials flow.
+            # Continuing with what we have is not an option when we have nothing.
+            raise AuthException("Failed to load or obtain a valid access token.")
+
     def pre_request_hook(self):
         self._refresh_if_needed()
         super().pre_request_hook()