Guard rescale_noise_cfg against zero std

b/src/diffusers/guiders/guider_utils.py

@@ -0,0 +1,8 @@
+    """
+    std_text = noise_pred_text.std(dim=list(range(1, noise_pred_text.ndim)), keepdim=True)
+    std_cfg = noise_cfg.std(dim=list(range(1, noise_cfg.ndim)), keepdim=True)
+    # Avoid division by zero when std_cfg is zero, which can produce NaN/Inf in noise predictions
+    std_cfg = std_cfg.clamp(min=1e-8)
+    # rescale the results from guidance (fixes overexposure)
+    noise_pred_rescaled = noise_cfg * (std_text / std_cfg)
+    # mix with the original results from guidance by factor guidance_rescale to avoid "plain looking" images

src/diffusers/guiders/guider_utils.py

@@ -389,6 +389,8 @@ def rescale_noise_cfg(noise_cfg, noise_pred_text, guidance_rescale=0.0):
     """
     std_text = noise_pred_text.std(dim=list(range(1, noise_pred_text.ndim)), keepdim=True)
     std_cfg = noise_cfg.std(dim=list(range(1, noise_cfg.ndim)), keepdim=True)
+    # Avoid division by zero when std_cfg is zero, which can produce NaN/Inf in noise predictions
+    std_cfg = std_cfg.clamp(min=1e-8)
     # rescale the results from guidance (fixes overexposure)
     noise_pred_rescaled = noise_cfg * (std_text / std_cfg)
     # mix with the original results from guidance by factor guidance_rescale to avoid "plain looking" images