The bug

The method net.minecraft.client.resources.ClientPackSource.downloadAndSelectResourcePack(String, String) (Mojang name) does not log the exception stack trace when applying the resource pack fails (message "Pack application failed").

Here this is especially problematic because it handles any kind of Throwable and not a specific type. For example MC-172198 describes a NullPointerException and it is very difficult to find out why it occurred without stack trace.