recover from failed JSON parse attempt

synapse_invite_checker/invite_checker.py

@@ -249,10 +249,12 @@ class InviteChecker:
 
         # Update cache if expired
         if current_time - self.cache_timestamp > self.cache_expiry_time:
+            self.allow_all_invites_on_error = False
             yield self.update_blocklist_allowlist()
 
         if self.allow_all_invites_on_error:
             logger.info("Skipping allowlist/blocklist checks because of previous JSON fetch failure.")
+            self.allow_all_invites_on_error = False
             returnValue((set(), set(), set()))
 
         # Return cached blocklist, allowlist, and blocklist room IDs