Fix some issues found by Sentry (#6962)

app/actions/remote/post.ts

@@ -544,9 +544,15 @@ export const fetchPostAuthors = async (serverUrl: string, posts: Post[], fetchOn
         }
 
         if (promises.length) {
-            const result = await Promise.all(promises);
-            const authors = result.flat();
+            const authorsResult = await Promise.allSettled(promises);
+            const result = authorsResult.reduce<UserProfile[][]>((acc, item) => {
+                if (item.status === 'fulfilled') {
+                    acc.push(item.value);
+                }
+                return acc;
+            }, []);
 
+            const authors = result.flat();
             if (!fetchOnly && authors.length) {
                 await operator.handleUsers({
                     users: authors,

app/managers/session_manager.ts

@@ -78,8 +78,9 @@ class SessionManager {
     };
 
     private clearCookiesForServer = async (serverUrl: string) => {
-        this.clearCookies(serverUrl, false);
         if (Platform.OS === 'ios') {
+            this.clearCookies(serverUrl, false);
+
             // Also delete any cookies that were set by react-native-webview
             this.clearCookies(serverUrl, true);
         } else if (Platform.OS === 'android') {

app/screens/navigation.ts

@@ -475,12 +475,17 @@ export function goToScreen(name: string, title: string, passProps = {}, options
     });
 }
 
-export function popTopScreen(screenId?: string) {
-    if (screenId) {
-        Navigation.pop(screenId);
-    } else {
-        const componentId = NavigationStore.getVisibleScreen();
-        Navigation.pop(componentId);
+export async function popTopScreen(screenId?: string) {
+    try {
+        if (screenId) {
+            await Navigation.pop(screenId);
+        } else {
+            const componentId = NavigationStore.getVisibleScreen();
+            await Navigation.pop(componentId);
+        }
+    } catch (error) {
+        // RNN returns a promise rejection if there are no screens
+        // atop the root screen to pop. We'll do nothing in this case.
     }
 }