Add debug message to RCTShadowView when we insert a subview incorrectly

Summary:
@public
This will provide a more useful error message and hopefully allow us to debug the issue further.

Reviewed By: JoshuaGross

Differential Revision: D17793693

fbshipit-source-id: 848ae658200ea5e3892d8a88888599c1c248c994

React/Views/RCTShadowView.m

@@ -227,6 +227,15 @@ - (void)insertReactSubview:(RCTShadowView *)subview atIndex:(NSInteger)atIndex
 {
  RCTAssert(self.canHaveSubviews, @"Attempt to insert subview inside leaf view.");
 
+ // TODO(T55181688): Delete after getting crashes with a view hierarchy.
+ if (atIndex > [_reactSubviews count]) {
+ RCTShadowView *ancestor = self;
+ for (NSInteger i = 0; i < 5 && [ancestor superview]; i++) {
+ ancestor = [ancestor superview];
+ }
+ RCTAssert(NO, @"Tried to insert subview on view %@ with ancestor description %@", self, ancestor);
+ }
+
  [_reactSubviews insertObject:subview atIndex:atIndex];
  if (![self isYogaLeafNode]) {
  YGNodeInsertChild(_yogaNode, subview.yogaNode, (uint32_t)atIndex);