[models] file open error check

src/models.c

@@ -1291,6 +1291,12 @@ static VertexData LoadOBJ(const char *fileName)
 
     objFile = fopen(fileName, "rt");
     
+    if (objFile == NULL)
+    {
+        TraceLog(WARNING, "[%s] OBJ file could not be opened", fileName);
+        return vData;
+    }
+
     // First reading pass: Get numVertex, numNormals, numTexCoords, numTriangles
     // NOTE: vertex, texcoords and normals could be optimized (to be used indexed on faces definition)
     // NOTE: faces MUST be defined as TRIANGLES, not QUADS