api [nfc]: Simplify move data parsing with null-checks

Signed-off-by: Zixuan James Li <[email protected]>

Author: PIG208

lib/api/model/events.dart

@@ -811,27 +811,19 @@ class UpdateMessageMoveData {
       return null;
     }
 
-    if (origStreamId == null || newStreamId == null) {
+    return UpdateMessageMoveData(
       // The `stream_id` field (aka origStreamId) is documented to be present on moves;
       // newStreamId should not be null either because it falls back to origStreamId.
-      throw FormatException('Malformed UpdateMessageEvent: move but no origStreamId');
-    }
-    if (origTopic == null || newTopic == null) {
-      // The `orig_subject` field (aka origTopic) is documented to be present on moves;
-      // newTopic should not be null either because it falls back to origTopic.
-      throw FormatException('Malformed UpdateMessageEvent: move but no origTopic');
-    }
-    if (propagateMode == null) {
+      origStreamId: origStreamId!,
+      newStreamId: newStreamId!,
+
       // The `propagate_mode` field (aka propagateMode) is documented to be present on moves.
-      throw FormatException('Malformed UpdateMessageEvent: move but no propagateMode');
-    }
+      propagateMode: propagateMode!,
 
-    return UpdateMessageMoveData(
-      origStreamId: origStreamId,
-      newStreamId: newStreamId,
-      propagateMode: propagateMode,
-      origTopic: origTopic,
-      newTopic: newTopic,
+      // The `orig_subject` field (aka origTopic) is documented to be present on moves;
+      // newTopic should not be null either because it falls back to origTopic.
+      origTopic: origTopic!,
+      newTopic: newTopic!,
     );
   }
 }

test/model/message_test.dart

@@ -427,7 +427,7 @@ void main() {
         'stream_id': 1,
         'new_stream_id': 2,
         'orig_subject': null,
-      })).throws<FormatException>();
+      })).throws();
     });
 
     test('move but no subject or new_stream_id', () async {
@@ -441,15 +441,15 @@ void main() {
       await check(setupAndHandleEvent({ ...baseMoveJson,
         'stream_id': null,
         'new_stream_id': 2,
-      })).throws<FormatException>();
+      })).throws();
     });
 
     test('move but no propagate_mode', () async {
       await check(setupAndHandleEvent({ ...baseMoveJson,
         'orig_subject': 'foo',
         'subject': 'bar',
         'propagate_mode': null,
-      })).throws<FormatException>();
+      })).throws();
     });
   });