(not a teacher)
I think of phrases like this as having an unspoken but understood "it" at the end of them.
However, "calls for" sounds odd to me without the "it".
And yet, the sentence,"We'll do whatever the situation calls for."
sounds perfectly fine.
I wouldn't say that they're errors. This form is widely accepted as far as I can tell from my own
experience. I couldn't cite a rule for you, though. This is simply how the language grew.
Student or Learner