Solve infinite looping error for scalar variable

Author: Dhruvanshu-Joshi

pytensor/tensor/rewriting/subtensor.py

@@ -413,7 +413,10 @@ def local_replace_slice(fgraph, node):
             idx_flag = True
             start = None
 
-        if extract_constant(stop, only_process_constants=True) == x.type.shape[dim]:
+        if (
+            x.type.shape[dim] is not None
+            and extract_constant(stop, only_process_constants=True) == x.type.shape[dim]
+        ):
             idx_flag = True
             stop = None
 
@@ -423,8 +426,13 @@ def local_replace_slice(fgraph, node):
 
         new_idxs[dim] = slice(start, stop, step)
 
-    assert node.outputs[0].type == x[tuple(new_idxs)].type
     if idx_flag is True:
+        try:
+            assert node.outputs[0].type == x[tuple(new_idxs)].type
+        except AssertionError:
+            raise AssertionError(
+                f"The type of the returned variable {x[tuple(new_idxs)].type} did not match with the type of the original variable {node.outputs[0].type}"
+            )
         return [x[tuple(new_idxs)]]