TypeError: 'NoneType' object is not subscriptable after LTXV Add Latents

[Zueuk]

Not sure exactly why, but sometimes after manipulating latents with LTXV Add Latents I get this error

".../ComfyUI-LTXVideo/latents.py", line 80, in select_latents
    s["noise_mask"] = s["noise_mask"][:, :, start_idx : end_idx + 1, :, :]
TypeError: 'NoneType' object is not subscriptable

The Frames Concat Latent node from RES4LYF, which seems to perform exactly the same operation, does not cause this problem.