loader SvgLoader: return null if transform attribute invalid

In transform matrix parsing, null is returned if any of the matrices are invalid.

src/loaders/svg/tvgSvgLoader.cpp

@@ -659,8 +659,10 @@ static Matrix* _parseTransformationMatrix(const char* value)
             _matrixCompose(matrix, &tmp, matrix);
         }
     }
-error:
     return matrix;
+error:
+    if (matrix) free(matrix);
+    return nullptr;
 }