fix(ddim): validate eta is in [0, 1] in DDIMPipeline

src/diffusers/pipelines/ddim/pipeline_ddim.py

@@ -12,6 +12,8 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
+import logging
+
 import torch
 
 from ...models import UNet2DModel
@@ -21,6 +23,9 @@
 from ..pipeline_utils import DiffusionPipeline, ImagePipelineOutput
 
 
+logger = logging.getLogger(__name__)
+
+
 if is_torch_xla_available():
     import torch_xla.core.xla_model as xm
 
@@ -129,6 +134,13 @@ def __call__(
         else:
             image_shape = (batch_size, self.unet.config.in_channels, *self.unet.config.sample_size)
 
+        if not 0.0 <= eta <= 1.0:
+            logger.warning(
+                f"`eta` should be between 0 and 1 (inclusive), but received {eta}. "
+                "A value of 0 corresponds to DDIM and 1 corresponds to DDPM. "
+                "Unexpected results may occur for values outside this range."
+            )
+
         if isinstance(generator, list) and len(generator) != batch_size:
             raise ValueError(
                 f"You have passed a list of generators of length {len(generator)}, but requested an effective batch"