Only compare OS versions if `dig` was successful

Signed-off-by: RD WebDesign <github@rdwebdesign.com.br>

advanced/Scripts/piholeDebug.sh

@@ -394,6 +394,13 @@ os_check() {
     # Extract dig response
     response="${cmdResult%%$'\n'*}"
 
+    log_write "${INFO} dig return code:  ${digReturnCode}"
+    log_write "${INFO} dig response:  ${response}"
+
+    if [ "${response}" -ne 0 ]; then
+        log_write "${CROSS} Distro: ${COL_RED}${detected_os^}${COL_NC}"
+        log_write "${CROSS} Error:  ${COL_RED}dig command failed - Unable to check OS${COL_NC}"
+    else
         IFS=" " read -r -a supportedOS < <(echo "${response}" | tr -d '"')
         for distro_and_versions in "${supportedOS[@]}"
         do
@@ -414,9 +421,6 @@ os_check() {
             fi
         done
 
-    log_write "${INFO} dig return code:  ${digReturnCode}"
-    log_write "${INFO} dig response:  ${response}"
-
         if [ "$valid_os" = true ]; then
             log_write "${TICK} Distro:  ${COL_GREEN}${detected_os^}${COL_NC}"
 
@@ -430,6 +434,7 @@ os_check() {
             log_write "${CROSS} Distro:  ${COL_RED}${detected_os^}${COL_NC}"
             log_write "${CROSS} Error: ${COL_RED}${detected_os^} is not a supported distro (${FAQ_HARDWARE_REQUIREMENTS})${COL_NC}"
         fi
+    fi
 }
 
 diagnose_operating_system() {