Arm backend: Replace asserts with ValueError for slicing constraints (#10748)

The existing code used assertions to validate slicing parameters (e.g.,
size must be positive and within dimension limits). This has been
changed to raise ValueError with descriptive error messages to provide
clearer feedback and robustness for invalid inputs when using
aten.slice_copy.Tensor.

Signed-off-by: Sebastian Larsson <[email protected]>

Author: Sebastian-Larsson

backends/arm/operators/op_slice.py

@@ -68,8 +68,16 @@ def define_node(
         end_index = _fixup_end(end, shape, dim)
         size = end_index - start_index
 
-        assert size > 0
-        assert size <= shape[dim]
+        if size <= 0:
+            raise ValueError(
+                f"The calculated slice size must be positive. Got {size=} "
+                f"with {start_index=} and {end_index=}."
+            )
+        if size > shape[dim]:
+            raise ValueError(
+                f"The calculated slice size cannot be greater than the dimension size"
+                f". Got {size=} and {shape[dim]=}."
+            )
 
         # Convert aten args to Tosa's start and size attributes and in TOSA dim order.
         attr = ts.TosaSerializerAttribute()
@@ -122,8 +130,16 @@ def define_node(
         end_index = _fixup_end(end, shape, dim)
         size = end_index - start_index
 
-        assert size > 0
-        assert size <= shape[dim]
+        if size <= 0:
+            raise ValueError(
+                f"The calculated slice size must be positive. Got {size=} "
+                f"with {start_index=} and {end_index=}."
+            )
+        if size > shape[dim]:
+            raise ValueError(
+                f"The calculated slice size cannot be greater than the dimension size"
+                f". Got {size=} and {shape[dim]=}."
+            )
 
         # Convert aten args to Tosa's start and size shape_t tensors and in TOSA dim order.
         starts = [