test-repo/changelog_unreleased/api/13397.md

[BREAKING] undefined and null are not passed to plugin's print function (#13397 by @fisker)

If your plugin happened to use print to print them, please check them in the parent node instead.

function print(path, print) {
-  const value = path.getValue();
-  if (!value?.type) {
-    return String(value);
-  }

-  return path.map(print, "values");

+  return path.map((childPath) => {
+    const value = childPath.getValue();
+    return value?.type ? print() : String(value);
+  }, "values");
}