fix environ check

acestep/pipeline_ace_step.py

@@ -129,7 +129,7 @@ class ACEStepPipeline:
             self.dtype = torch.float16
         if device.type == "mps":
             self.dtype = torch.float32
-        if len(os.environ['COLAB_FREE']):
+        if 'COLAB_FREE' in os.environ and len(os.environ['COLAB_FREE']):
             self.dtype = torch.float16
         self.device = device
         self.loaded = False