The latent gets passed straight through unaltered, if it's empty (i.e from a 'Empty Latent Image' node) FLOAT outputs the first value, otherwise it outputs the second value
https://github.com/Koushakur/ComfyUI-DenoiseChooser
git clone https://github.com/Koushakur/ComfyUI-DenoiseChooser
comfy node install comfyui-denoisechooser