added adb serial found check

reinstall-magisk-on-lineageos

@@ -5,6 +5,10 @@ set -e
 PHONE_ADB_SERIAL_NUMBER=${ADB_DEVICE} # The adb serial number can be found by running `adb devices`.
 if [$PHONE_ADB_SERIAL_NUMBER = '']; then
     PHONE_ADB_SERIAL_NUMBER=$(echo $(adb devices) | sed -rn 's/(^|(.* ))([^ ]*) device(( .*)|$)/\3/; T; p; q')
+    if [[ -n $PHONE_ADB_SERIAL_NUMBER ]]
+        print_message "ERROR: no suitable phone connected"
+        exit 1
+    fi
 fi
 
 print_message() {