wip store [nfc]: pull out _triagePollRequestError

Author: gnprice

lib/model/store.dart

@@ -949,30 +949,8 @@ class UpdateMachine {
           if (_disposed) return;
 
           store.isLoading = true;
-          bool shouldReportToUser;
-          switch (e) {
-            case NetworkException(cause: SocketException()):
-              // A [SocketException] is common when the app returns from sleep.
-              shouldReportToUser = false;
-
-            case NetworkException():
-            case Server5xxException():
-              shouldReportToUser = true;
-
-            case ZulipApiException(httpStatus: 429):
-            case ZulipApiException(code: 'RATE_LIMIT_HIT'):
-              // TODO(#946) handle rate-limit errors more generally, in ApiConnection
-              shouldReportToUser = true;
-
-            default:
-              rethrow;
-          }
-
-          assert(debugLog('Transient error polling event queue for $store: $e\n'
-              'Backing off, then will retry…'));
-          if (shouldReportToUser) {
-            _maybeReportToUserTransientError(e);
-          }
+          final shouldRetry = _triagePollRequestError(e);
+          if (!shouldRetry) rethrow;
           await (backoffMachine ??= BackoffMachine()).wait();
           if (_disposed) return;
           assert(debugLog('… Backoff wait complete, retrying poll.'));
@@ -1046,6 +1024,39 @@ class UpdateMachine {
     reportErrorToUserBriefly(null);
   }
 
+  /// Sort out an error from the network request in [poll].
+  ///
+  /// If the request should be retried, this method returns true,
+  /// after reporting the error if appropriate to the user and/or developer.
+  /// Otherwise, this method returns false with no side effects.
+  bool _triagePollRequestError(Object error) {
+    bool shouldReportToUser;
+    switch (error) {
+      case NetworkException(cause: SocketException()):
+        // A [SocketException] is common when the app returns from sleep.
+        shouldReportToUser = false;
+
+      case NetworkException():
+      case Server5xxException():
+        shouldReportToUser = true;
+
+      case ZulipApiException(httpStatus: 429):
+      case ZulipApiException(code: 'RATE_LIMIT_HIT'):
+        // TODO(#946) handle rate-limit errors more generally, in ApiConnection
+        shouldReportToUser = true;
+
+      default:
+        return false;
+    }
+
+    assert(debugLog('Transient error polling event queue for $store: $error\n'
+        'Backing off, then will retry…'));
+    if (shouldReportToUser) {
+      _maybeReportToUserTransientError(error);
+    }
+    return true;
+  }
+
   /// Report an error in [poll], if appropriate, to the user and/or developer.
   void _reportPollError(Object error) {
     switch (error) {