return instead of exit

install.sh

@@ -37,7 +37,7 @@ function assert_supported_distro {
     distro=$(grep -oP '^ID=\K(.*)' /etc/os-release)
     >&2 echo "unsupported GNU/Linux distribution: $distro"
     >&2 echo 'only debian-like OR arch-like currently supported'
-    return
+    return 10
   fi
 }
 
@@ -54,14 +54,14 @@ function execute_miaou_lib {
 function assert_bash {
   if [[ $SHELL != bash ]]; then
     >&2 echo "you are running on SHELL=$SHELL. Bash expected!"
-    return
+    return 11
   fi
 }
 
 function sudo_root {
   if [[ "$UID" -ne 0 ]] && ! sudo -vp 'SUDO privilege required: '; then
     >&2 echo "canceled"
-    return
+    return 12
   fi
 }
 ## MAIN