[lib] Avoid useless updateRelationships call when logged out in handl…

…eFarcasterMutuals

Summary: This addresses [ENG-9229](https://linear.app/comm/issue/ENG-9229/not-logged-in-when-calling-updaterelationships).

Test Plan: We use a similar strategy [here](https://github.com/CommE2E/comm/blob/7488a4e6fc3a832b2ad7f54df401e04935b981d7/lib/keyserver-conn/recovery-utils.js#L164-L171), which has been tested. This change is safe because it's simple and is using an approach I've tested before

Reviewers: will, varun

Reviewed By: varun

Subscribers: tomek

Differential Revision: https://phab.comm.dev/D13298

lib/components/farcaster-data-handler.react.js

@@ -63,6 +63,15 @@ function FarcasterDataHandler(props: Props): React.Node {
 
   const prevCanQueryRef = React.useRef<?boolean>();
 
+  // It's possible for the user to log out while handleFarcasterMutuals below
+  // is running. It's not a big deal, but this can lead to a useless server call
+  // at the end. To avoid that useless server call, we want to check whether the
+  // user is logged in beforehand, but the value of loggedIn bound in the
+  // callback will be outdated. Instead, we can check this ref, which will be
+  // updated on every render.
+  const loggedInRef = React.useRef(loggedIn);
+  loggedInRef.current = loggedIn;
+
   const handleFarcasterMutuals = React.useCallback(async () => {
     const canQuery = isActive && !!fid && loggedIn;
     if (canQuery === prevCanQueryRef.current) {
@@ -100,6 +109,10 @@ function FarcasterDataHandler(props: Props): React.Node {
       [(currentUserID: string)]: fid,
     };
 
+    if (!loggedInRef.current) {
+      return;
+    }
+
     void dispatchActionPromise(
       updateRelationshipsActionTypes,
       createThreadsAndRobotextForFarcasterMutuals(