Fix error during field access in VM

Tuple constructors can't have nkExprColonExpr but may contain NimNodes
of that kind.

Fixes #4952

tests/vm/t4952.nim

@@ -0,0 +1,17 @@
+import macros
+
+proc doCheck(tree: NimNode) =
+  let res: tuple[n: NimNode] = (n: tree)
+  assert: tree.kind == res.n.kind
+  for sub in tree:
+    doCheck(sub)
+
+macro id(body: untyped): untyped =
+  doCheck(body)
+
+id(foo((i: int)))
+
+static:
+  let tree = newTree(nnkExprColonExpr)
+  let t = (n: tree)
+  assert: t.n.kind == tree.kind