[FlaxStableDiffusionPipeline] fix bug when nsfw is detected (#832)

fix nsfw bug

Author: patil-suraj

src/diffusers/pipelines/stable_diffusion/pipeline_flax_stable_diffusion.py

@@ -291,7 +291,8 @@ def __call__(
             # block images
             if any(has_nsfw_concept):
                 for i, is_nsfw in enumerate(has_nsfw_concept):
-                    images[i] = np.asarray(images_uint8_casted[i])
+                    if is_nsfw:
+                        images[i] = np.asarray(images_uint8_casted[i])
 
             images = images.reshape(num_devices, batch_size, height, width, 3)
         else: