diff --git a/lib/hooks/thread-search-hooks.js b/lib/hooks/thread-search-hooks.js
--- a/lib/hooks/thread-search-hooks.js
+++ b/lib/hooks/thread-search-hooks.js
@@ -41,6 +41,7 @@
     async (usernamePrefix: string) => {
       if (usernamePrefix.length === 0) {
         filterAndSetUserResults([]);
+        return;
       }
 
       const { userInfos } = await legacyCallSearchUsers(usernamePrefix);