Fix image meory leak

Author: kimkulling

src/widgets.cpp

@@ -66,6 +66,7 @@ static Image *loadIntoImageCache(Context &ctx, const char *filename) {
     int w, h, bytesPerPixel;
     unsigned char *data = stbi_load(filename, &w, &h, &bytesPerPixel, 0);
     if (data == nullptr) {
+        delete image;
         return nullptr;
     }