fix lottie crash during wrong input

com.unity.uiwidgets/Runtime/ui/painting.cs

     
     public class Skottie : NativeWrapper {
         public Skottie(string path) {
-            _setPtr(Skottie_Construct(path));
+            var Id = Skottie_Construct(path);
+            if(Id == IntPtr.Zero){
+                Debug.LogError($"cannot load lottie from {path}, please check file exist and valid");
+            }else {
+                _setPtr(Id);
+            }
         }
 
         public override void DisposePtr(IntPtr ptr) {

engine/src/lib/ui/painting/skottie.cc

   path = (char*)fileOut;
 #endif
   sk_sp<skottie::Animation> animation_ = skottie::Animation::MakeFromFile(path);
+  if(animation_ == nullptr){
+    return nullptr;
+  }
   return fml::MakeRefCounted<Skottie>(animation_);
 }
 
 UIWIDGETS_API(Skottie*)
 Skottie_Construct(char* path) {
   fml::RefPtr<Skottie> skottie = Skottie::Create(path);
+  if(skottie.get() == nullptr){
+    return nullptr;
+  }
-Skottie_Dispose(Skottie* ptr) { ptr->Release(); }
+Skottie_Dispose(Skottie* ptr) {
+  if(ptr == nullptr){
+      return;
+  }
+  ptr->Release();
+}
+  if(ptr == nullptr){
+      return;
+  }
-Skottie_Duration(Skottie* ptr) { return ptr->duration(); }
+Skottie_Duration(Skottie* ptr) {
+  if(ptr == nullptr){
+      return 0;
+  }
+  return ptr->duration(); }
 }  // namespace uiwidgets