add check for getMissing function

[ariaieboy]

1️⃣ Is this something that is wanted/needed? Did you create an issue / discussion about it first?
#3357
2️⃣ Does it contain multiple, unrelated changes? Please separate the PRs out.
no
3️⃣ Does it include tests, if possible? (Not a deal-breaker, just a nice-to-have)
no
4️⃣ Please include a thorough description of the improvement and reasons why it's useful.
i've just add a method_exists check to resolve the issue that i mentioned
5️⃣ Thanks for contributing! 🙌

[calebporzio]

Thanks!