chore(node): normalize config.sh to return empty string (#3502)

normalize config.sh get_config_value:
- If key not found or value is "null", returns empty string. Otherwise,
returns value

ic-os/components/misc/config/setupos/config.sh

@@ -5,9 +5,18 @@
 # Retrieves a value from the config.json file using a JSON path.
 # Arguments:
 #   $1 - JSON path to the desired value (e.g., '.icos_settings.nns_urls')
-# Note: If the key is not found, this function will return null.
+# Returns:
+#   If key is not found or value is "null", returns empty string.
+#   Otherwise, returns value.
 function get_config_value() {
     local CONFIG_FILE="/var/ic/config/config.json"
     local key=$1
-    jq -r "${key}" "${CONFIG_FILE}"
+
+    local value=$(jq -r "${key}" "${CONFIG_FILE}")
+
+    if [[ "${value}" == "null" ]]; then
+        echo ""
+    else
+        echo "${value}"
+    fi
 }

ic-os/components/setupos-scripts/check-network.sh

@@ -101,14 +101,13 @@ function print_network_settings() {
     echo "* Printing user defined network settings..."
     echo "  IPv6 Prefix : ${ipv6_prefix}"
     echo "  IPv6 Gateway: ${ipv6_gateway}"
-    if [[ -n ${ipv4_address} && "${ipv4_address}" != "null" &&
-        -n ${ipv4_prefix_length} && "${ipv4_prefix_length}" != "null" &&
-        -n ${ipv4_gateway} && "${ipv4_gateway}" != "null" ]]; then
+
+    if [[ -n ${ipv4_address} && -n ${ipv4_prefix_length} && -n ${ipv4_gateway} ]]; then
         echo "  IPv4 Address: ${ipv4_address}"
         echo "  IPv4 Prefix Length: ${ipv4_prefix_length}"
         echo "  IPv4 Gateway: ${ipv4_gateway}"
     fi
-    if [[ -n ${domain_name} && "${domain_name}" != "null" ]]; then
+    if [[ -n ${domain_name} ]]; then
         echo "  Domain name: ${domain_name}"
     fi
     echo " "
@@ -214,13 +213,11 @@ main() {
         get_network_settings
         print_network_settings
 
-        if [[ -n ${domain_name} && "${domain_name}" != "null" ]]; then
+        if [[ -n ${domain_name} ]]; then
             validate_domain_name
         fi
 
-        if [[ -n ${ipv4_address} && "${ipv4_address}" != "null" &&
-            -n ${ipv4_prefix_length} && "${ipv4_prefix_length}" != "null" &&
-            -n ${ipv4_gateway} && "${ipv4_gateway}" != "null" ]]; then
+        if [[ -n ${ipv4_address} && -n ${ipv4_prefix_length} && -n ${ipv4_gateway} ]]; then
             setup_ipv4_network
             ping_ipv4_gateway
         fi