Fix OSS-Fuzz #69765

[nielsdos]

You cannot return or yield a reference to a nullsafe chain. This was
checked already in zend_compile_return but not yet in
zend_compile_yield.

First commit fixes the bug, second commit factors out the common code.

[jorgsowa]

The current message Cannot take reference is unfortunate. You described the limitation much better in the PR description by You cannot return or yield a reference to a nullsafe chain..

[nielsdos]

I'm fine with making the message specialised but I'll wait first for Ilija and/or Dmitry to comment.
EDIT: and changing messages for existing compile errors seems like master-only material.

[iluuu1994]

LGTM, thanks!

You cannot return or yield a reference to a nullsafe chain.

The error occurs before the return, when trying to acquire the reference. ?-> can return the temporary value null, which cannot be turned into a reference, as it would have no effect.

[nielsdos]

The error occurs before the return, when trying to acquire the reference. ?-> can return the temporary value null, which cannot be turned into a reference, as it would have no effect.

Right ofc, this description is indeed more accurate.