Update glTF2Asset.inl

Fix possible nullptr-dereferencing.

code/glTF2Asset.inl

@@ -1359,10 +1359,12 @@ inline void Asset::Load(const std::string& pFile, bool isBinary)
 
     // Force reading of skins since they're not always directly referenced
     if (Value* skinsArray = FindArray(doc, "skins")) {
+        if ( nullptr != skinsArray ) {
                 for (unsigned int i = 0; i < skinsArray->Size(); ++i) {
                     skins.Retrieve(i);
                 }
 	}
+    }
 
     if (Value* animsArray = FindArray(doc, "animations")) {
         for (unsigned int i = 0; i < animsArray->Size(); ++i) {