[MC-75726] Broken error message when loading (broken?) resource packs

When loading a certain resource pack, the broken error message

ResourcePack: ignored non-lowercase namespace: %s in %s

is triggered:

[15:11:34] [Client thread/INFO]: Created: 512x512 textures-atlas
[15:11:46] [Client thread/INFO]: Reloading ResourceManager: Default, XDBMisaPatchV1.4.zip
[15:11:46] [Client thread/WARN]: ResourcePack: ignored non-lowercase namespace: %s in %s
[15:11:46] [Client thread/INFO]: SoundSystem shutting down...

Steps to reproduce:

Download and install XDB's Misa Realistic Resource Patch [1.8]
Start Minecraft
Use the resource pack