-i ignores the -a arguments

[wwalker]

If one runs:

j4-make-config -i -a config.after -a config.before

then j4-make-config creates a new config made from:

• config.base
• themes/grubox

j4-make-config silently ignores all options after it -i

If one, instead, puts -i after the -a options, then an error is reported:

Error: theme -i does not exist.