fix(own): read nullability through the own wrapper

`own (T?)` resolves to the nullable pointer, so a `None` initializer is valid there.

App/lib/core/Gen/GenApi.vp

@@ -130,14 +130,21 @@ def strict_obs() -> int:
 
 
 # annotation_is_nullable - 1 when a type annotation carries the `?` suffix (`NullableT[T]`).
+# `own` keeps an existing pointer layer, so it is transparent for nullability: `own (T?)` is nullable.
 def annotation_is_nullable(ann: ast.AST*) -> int:
-    if ann is None or ann.kind() != ast.ASTKind.Subscript: return 0
-    sb: ast.Subscript* = ast.Subscript*(ann)
-    if sb.value is None or sb.value.kind() != ast.ASTKind.Name: return 0
-    nm: ast.Name* = ast.Name*(sb.value)
-    if nm.id is None: return 0
-    if string.strcmp(nm.id, "OptionT") == 0: return 1
-    if string.strcmp(nm.id, "NullableT") == 0: return 1
+    node: ast.AST* = ann
+    depth: int = 0
+    while node is not None and depth < 8:
+        if node.kind() != ast.ASTKind.Subscript: return 0
+        sb: ast.Subscript* = ast.Subscript*(node)
+        if sb.value is None or sb.value.kind() != ast.ASTKind.Name: return 0
+        nm: ast.Name* = ast.Name*(sb.value)
+        if nm.id is None: return 0
+        if string.strcmp(nm.id, "OptionT") == 0: return 1
+        if string.strcmp(nm.id, "NullableT") == 0: return 1
+        if string.strcmp(nm.id, "OwnT") != 0: return 0
+        node = sb.slice
+        depth += 1
     return 0