Ensure that the uncommon __unloadNode codepath does not unintentionally trigger node removal.

AsyncDisplayKit/ASDisplayNode.mm

@@ -352,8 +352,9 @@ static ASDisplayNodeMethodOverrides GetASDisplayNodeMethodOverrides(Class c)
 - (void)__unloadNode
 {
   ASDisplayNodeAssertThreadAffinity(self);
+  ASDisplayNodeAssert([self isNodeLoaded], @"Implementation shouldn't call __unloadNode if not loaded: %@", self);
   ASDN::MutexLocker l(_propertyLock);
-  
+
   if (_flags.layerBacked)
     _pendingViewState = [_ASPendingState pendingViewStateFromLayer:_layer];
   else

AsyncDisplayKit/Details/_ASDisplayView.mm

@@ -151,8 +151,11 @@
         needsSupernodeRemoval = YES;
       }
     } else {
-      // If supernode is loaded but our superview is nil, the user manually removed us, so disconnect supernode.
-      needsSupernodeRemoval = supernodeLoaded;
+      // If supernode is loaded but our superview is nil, the user likely manually removed us, so disconnect supernode.
+      // The unlikely alternative: we are in __unloadNode, with shouldRasterizeSubnodes just having been turned on.
+      // In the latter case, we don't want to disassemble the node hierarchy because all views are intentionally being destroyed.
+      BOOL nodeIsRasterized = ((_node.hierarchyState & ASHierarchyStateRasterized) == ASHierarchyStateRasterized);
+      needsSupernodeRemoval = (supernodeLoaded && !nodeIsRasterized);
     }
     
     if (needsSupernodeRemoval) {

AsyncDisplayKit/Private/_ASPendingState.m

@@ -798,8 +798,13 @@ static UIColor *defaultTintColor = nil;
     view.accessibilityIdentifier = accessibilityIdentifier;
 }
 
+// FIXME: Make this more efficient by tracking which properties are set rather than reading everything.
 + (_ASPendingState *)pendingViewStateFromLayer:(CALayer *)layer
 {
+  if (!layer) {
+    return nil;
+  }
+  
   _ASPendingState *pendingState = [[_ASPendingState alloc] init];
   
   pendingState.anchorPoint = layer.anchorPoint;
@@ -877,8 +882,13 @@ static UIColor *defaultTintColor = nil;
   return pendingState;
 }
 
+// FIXME: Make this more efficient by tracking which properties are set rather than reading everything.
 + (_ASPendingState *)pendingViewStateFromView:(UIView *)view
 {
+  if (!view) {
+    return nil;
+  }
+  
   _ASPendingState *pendingState = [[_ASPendingState alloc] init];
   
   CALayer *layer = view.layer;