message: Handled invalid values for system item prop
diff: @@ -60,14 +60,16 @@ using namespace facebook::react;
  self.button.accessibilityIdentifier = testID;
  NSString *systemItemVal = [[NSString alloc] initWithUTF8String: newViewProps.systemItem.c_str()];
  if (systemItemVal.length) {
  - UIBarButtonSystemItem systemItem = [self systemItem:systemItemVal];
  - self.button = [[UIBarButtonItem alloc] initWithBarButtonSystemItem:systemItem target:self action:@selector(buttonPressed)];
  + NSInteger systemItem = [self systemItem:systemItemVal];
  + if (systemItem >= 0) {
  + self.button = [[UIBarButtonItem alloc] initWithBarButtonSystemItem:(UIBarButtonSystemItem) systemItem target:self action:@selector(buttonPressed)];
  self.button.accessibilityIdentifier = testID;
  }
  + }
  [super updateProps:props oldProps:oldProps];
  }
  --(UIBarButtonSystemItem)systemItem:(NSString*)val
  +-(NSInteger)systemItem:(NSString*)val
  {
  if ([val isEqualToString:@"done"]) return UIBarButtonSystemItemDone;
  if ([val isEqualToString:@"cancel"]) return UIBarButtonSystemItemCancel;
  @@ -91,7 +93,8 @@ using namespace facebook::react;
  if ([val isEqualToString:@"rewind"]) return UIBarButtonSystemItemRewind;
  if ([val isEqualToString:@"fast-forward"]) return UIBarButtonSystemItemFastForward;
  if ([val isEqualToString:@"undo"]) return UIBarButtonSystemItemUndo;
  - return UIBarButtonSystemItemRedo;
  + if ([val isEqualToString:@"redo"]) return UIBarButtonSystemItemRedo;
  + return -1;
  }
  -(void)buttonPressed
  