Fix crash when accessing nullptr imageRequest

Summary:
ImageState if created with default constructor is created with `imageRequest_` being nullptr.
Calling `getObserverCoordinator()` on it was causing a crash.

We create initial state data with `imageRequest` populated.

Changelog: [Internal]

Reviewed By: shergin

Differential Revision: D19332711

fbshipit-source-id: 0266222551dbfb10b3f86e72a43d5306650fd09b

Author: sammy-SC

React/Fabric/Mounting/ComponentViews/Image/RCTImageComponentView.mm

@@ -20,6 +20,8 @@
 #import "RCTConversions.h"
 #import "RCTFabricComponentsPlugins.h"
 
+using namespace facebook::react;
+
 @interface RCTImageComponentView () <RCTImageResponseDelegate>
 @end
 
@@ -79,8 +81,7 @@ - (void)updateProps:(Props::Shared const &)props oldProps:(Props::Shared const &
   [super updateProps:props oldProps:oldProps];
 }
 
-- (void)updateState:(facebook::react::State::Shared const &)state
-           oldState:(facebook::react::State::Shared const &)oldState
+- (void)updateState:(State::Shared const &)state oldState:(State::Shared const &)oldState
 {
   _state = std::static_pointer_cast<ImageShadowNode::ConcreteState const>(state);
   auto _oldState = std::static_pointer_cast<ImageShadowNode::ConcreteState const>(oldState);

ReactCommon/fabric/components/image/ImageShadowNode.h

@@ -35,6 +35,14 @@ class ImageShadowNode final : public ConcreteViewShadowNode<
    */
   void setImageManager(const SharedImageManager &imageManager);
 
+  static ImageState initialStateData(
+      ShadowNodeFragment const &fragment,
+      SurfaceId const surfaceId,
+      ComponentDescriptor const &componentDescriptor) {
+    auto imageSource = ImageSource{ImageSource::Type::Invalid};
+    return {imageSource, {imageSource, nullptr}};
+  }
+
 #pragma mark - LayoutableShadowNode
 
   void layout(LayoutContext layoutContext) override;

ReactCommon/fabric/components/image/ImageState.h

@@ -24,8 +24,6 @@ class ImageState final {
         imageRequest_(
             std::make_shared<ImageRequest>(std::move(imageRequest))){};
 
-  ImageState() = default;
-
   /*
    * Returns stored ImageSource object.
    */