fixes #23306 nim cpp -r invalid code generation regression with closure iterators and try/catch-like constructions (#23317)

tests/cpp/t23306.nim

@@ -0,0 +1,12 @@
+discard """
+targets: "cpp"
+"""
+
+type K = object
+  h: iterator(f: K): K
+
+iterator d(g: K): K {.closure.} =
+  defer:
+    discard
+
+discard K(h: d)