sample_dpmpp_2m_sde no longer crashes when step == 1.

comfy/k_diffusion/sampling.py

@@ -628,6 +628,7 @@ def sample_dpmpp_2m_sde(model, x, sigmas, extra_args=None, callback=None, disabl
         if sigmas[i + 1] == 0:
             # Denoising step
             x = denoised
+            h = None
         else:
             # DPM-Solver++(2M) SDE
             t, s = -sigmas[i].log(), -sigmas[i + 1].log()