Fixes (#37)

* Don't create doas config if failed to install.

* Fix it better, previous change made it so that a value was required, could not just run setup.sh..

setup.sh

@@ -52,16 +52,17 @@ while getopts ":lb:h" arg; do
 	esac
 done
 
+# Alert on historic usage of `setup.sh BRANCH`.
+if [[ ! -z $1 && $1 != "-"* ]]; then
+	echo "ERROR: '$1' is not a valid option, please check your parameters and try again."
+	usage 1
+fi
+
 if [[ $branch == "" ]]; then
 	echo "Using default branch $BRANCH."
 	branch="$BRANCH"
 fi
 
-if [[ $1 != "-"* ]]; then
-	echo "ERROR: '$1' is not a valid option, please check your parameters and try again."
-	usage 1
-fi
-
 ## Main ##
 
 os="$(cat /etc/os-release)"