Transformed some errors into warnings.

src/image.cpp

@@ -40,7 +40,7 @@ const Image image::get(const string &digest, const uint16_t size)
         filename = settings::avatar_dir / "default";
         if (!fs::is_regular_file(filename))
         {
-            cerr << "Error: User not found and no default image set.\n";
+            cerr << "Warning: User not found and no default image set.\n";
             return { 2, img };
         }
     }

src/libravatarserv.cpp

@@ -64,7 +64,7 @@ int main()
     }
     else
     {
-        cerr << "Error " << std::to_string(image.error)
+        cerr << "Warning " << std::to_string(image.error)
              << ": Could not open file.\n";
         if (settings::settings.redirect_nouser)
         {