When calling `ag` I get the errror "cond: Wrong type argument: listp, ag/run-finished-hook

[halloleo]

When calling ag I get the error cond: Wrong type argument: listp, ag/run-finished-hook.

Environment & Version information

package ag-20201031.2202

executable ag version 2.1.0 (I know this is rather old, but I suspect the error is not related to this, but rather to the eg.el lisp code.)

Emacs version

GNU Emacs 27.1

Operating system

CentOS 6 (I know this is rather old, but ... see above.)