[Pattern] improve error handling in place()

masque/pattern.py

@@ -1411,7 +1411,9 @@ class Pattern(PortList, AnnotatableImpl, Mirrorable):
             other_copy.translate_elements(offset)
             self.append(other_copy)
         else:
-            assert not isinstance(other, Pattern)
+            if isinstance(other, Pattern):
+                raise PatternError('Must provide an `Abstract` (not a `Pattern`) when creating a reference. '
+                                   'Use `append=True` if you intended to append the full geometry.')
             ref = Ref(mirrored=mirrored)
             ref.rotate_around(pivot, rotation)
             ref.translate(offset)

masque/test/test_pattern.py

@@ -126,6 +126,14 @@ def test_pattern_flatten_repeated_ref_with_ports_raises() -> None:
         parent.flatten({"child": child}, flatten_ports=True)
 
 
+def test_pattern_place_requires_abstract_for_reference() -> None:
+    parent = Pattern()
+    child = Pattern()
+
+    with pytest.raises(PatternError, match='Must provide an `Abstract`'):
+        parent.place(child)
+
+
 def test_pattern_interface() -> None:
     source = Pattern()
     source.ports["A"] = Port((10, 20), 0, ptype="test")