1 files changed, 2 insertions, 0 deletions
diff --git a/registry/reg.py b/registry/reg.py
index b8f8af7..fcc47ac 100644
--- a/registry/reg.py
+++ b/registry/reg.py
@@ -1154,6 +1154,8 @@ class Registry:
                             # Resolve the type info to the actual type, so we get an accurate read for 'structextends'
                             while alias:
                                 typeinfo = self.lookupElementInfo(alias, self.typedict)
+                                if not typeinfo:
+                                    raise RuntimeError(f"Missing alias {alias}")
                                 alias = typeinfo.elem.get('alias')
 
                             typecat = typeinfo.elem.get('category')