fix(evil): add error handling for :h[elp] ex command

apropos throws up an arith-error trying to rank the results of matchless
regexp (which can result in a segfault on some systems; see #8532), and
is *incredibly* slow lookuping up short queries, so the command will now
abort if the query is just a regexp operator or less than 3 characters
long.

Fix: #8532

modules/editor/evil/autoload/ex.el

@@ -182,6 +182,13 @@ non-nil, a search is preformed against Doom's manual (with
              (funcall (or (command-remapping #'describe-function)
                           #'describe-function)
                       (evil-ex-completed-binding (match-string 1 query))))
+            ((or (string-match "^ *[^a-z0-9-_]$" query)
+                 (condition-case nil
+                     (ignore (string-match-p query ""))
+                   (invalid-regexp t)))
+             (user-error "Invalid query: %S" query))
+            ((< (string-width query) 3)
+             (user-error "Query too short (must be > 2 characters): %S" query))
             ((message "Searching for %S, this may take a while..." query)
              (apropos query t))))))