bug#27363: 26.0.50; Error with customize-group

[Glenn Morris]

Simen Heggestøyl wrote:

> Debugger entered--Lisp error: (wrong-type-argument listp (character))
>  widget-put((repeat character) :options ((125 59)))

This is the same thing as http://debbugs.gnu.org/25640; ie fallout from
plist-put changes.

Although the :options field for css-electric-keys seems pointless anyway,
since the repeat type doesn't support it. (Same for compilation-environment.)