[fix] : Fixed set -eu

Author: Hayao0819

build.sh

@@ -1220,10 +1220,8 @@ msg_debug "Use the default configuration file (${defaultconfig})."
 # Debug mode
 if [[ "${bash_debug}" = true ]]; then set -x -v; fi
 
-set +eu
-
 # Check for a valid channel name
-if [[ -n "${1}" ]]; then
+if [[ -n "${1+SET}" ]]; then
     case "$(bash "${tools_dir}/channel.sh" -n check "${1}")" in
         "incorrect")
             msg_error "Invalid channel ${1}" "1"
@@ -1237,6 +1235,9 @@ if [[ -n "${1}" ]]; then
             channel_name="${1}"
             ;;
     esac
+else
+    channel_dir="${script_path}/channels/${channel_name}"
+
 fi
 
 # Set for special channels
@@ -1246,8 +1247,6 @@ if [[ -d "${channel_dir}.add" ]]; then
 elif [[ "${channel_name}" = "clean" ]]; then
    "${tools_dir}/clean.sh" -w "$(realpath "${work_dir}")" $([[ "${debug}" = true ]] && echo -n "-d")
     exit 0
-else
-    channel_dir="${script_path}/channels/${channel_name}"
 fi
 
 # Check channel version