Tidy avahi utils

src/freedombone-utils-avahi

 }
 
 function mesh_avahi {
+    # shellcheck disable=SC2154
     chroot "$rootdir" apt-get -yq install avahi-utils avahi-dnsconfd
 
     decarray=( 1 2 3 4 5 6 7 8 9 0 )
         return
     fi
 
-    ${PROJECT_NAME}-mesh-install -f avahi
-    if [ ! "$?" = "0" ]; then
+    if ! "${PROJECT_NAME}-mesh-install" -f avahi; then
         echo $'Failed to install avahi'
         exit 68442
     fi
 
-    if [ $DEFAULT_DOMAIN_NAME ]; then
+    if [ "$DEFAULT_DOMAIN_NAME" ]; then
         sed -i "s|#host-name=.*|host-name=$LOCAL_NAME|g" /etc/avahi/avahi-daemon.conf
         sed -i "s|host-name=.*|host-name=$LOCAL_NAME|g" /etc/avahi/avahi-daemon.conf
     else