diff --git a/src/stores/FlairStore.js b/src/stores/FlairStore.js
index 9424503390..1d20148c0d 100644
--- a/src/stores/FlairStore.js
+++ b/src/stores/FlairStore.js
@@ -48,6 +48,9 @@ class FlairStore extends EventEmitter {
             //      reject: () => {}
             //  }
         };
+        this._usersInFlight = {
+            // This has the same schema as _usersPending
+        };
 
         this._debounceTimeoutID = null;
     }
@@ -125,12 +128,16 @@ class FlairStore extends EventEmitter {
         } catch (err) {
             // Propagate the same error to all usersInFlight
             Object.keys(this._usersInFlight).forEach((userId) => {
+                // The promise should always exist for userId, but do a null-check anyway
+                if (!this._usersInFlight[userId]) return;
                 this._usersInFlight[userId].reject(err);
             });
             return;
         }
         const updatedUserGroups = resp.users;
         Object.keys(this._usersInFlight).forEach((userId) => {
+            // The promise should always exist for userId, but do a null-check anyway
+            if (!this._usersInFlight[userId]) return;
             this._usersInFlight[userId].resolve(updatedUserGroups[userId] || []);
         });
     }