Hotfix: Corrupted data no longer saved to thread cache

Author: fourjr

CHANGELOG.md

@@ -6,6 +6,14 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/).
 This project mostly adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html);
 however, insignificant breaking changes do not guarantee a major version bump, see the reasoning [here](https://github.com/kyb3r/modmail/issues/319). If you're a plugin developer, note the "BREAKING" section.
 
+# v3.8.3
+
+This update is a quick hotfix for a weird behaviour experienced on 1 Feb 2021 where users were not properly cached.
+
+### Fixed
+
+- Corrupted data is no longer saved to thread cache.
+
 # v3.8.2
 
 ### Fixed

core/thread.py

@@ -1127,7 +1127,9 @@ async def find(
             )
             if channel:
                 thread = Thread(self, recipient or recipient_id, channel)
-                self.cache[recipient_id] = thread
+                if thread.recipient:
+                    # only save if data is valid
+                    self.cache[recipient_id] = thread
                 thread.ready = True
         return thread