If they set attributedString to nil twice, ignore the second one.

Author: Adlai-Holler

AsyncDisplayKit/ASTextNode.mm

@@ -336,14 +336,14 @@ - (BOOL)_needInvalidateRenderer:(CGSize)newSize
 
 - (void)setAttributedString:(NSAttributedString *)attributedString
 {
-  if (ASObjectIsEqual(attributedString, _attributedString)) {
-    return;
-  }
-
   if (attributedString == nil) {
     attributedString = [[NSAttributedString alloc] initWithString:@"" attributes:nil];
   }
 
+  if (ASObjectIsEqual(attributedString, _attributedString)) {
+    return;
+  }
+
   _attributedString = ASCleanseAttributedStringOfCoreTextAttributes(attributedString);
 
   // Sync the truncation string with attributes from the updated _attributedString