Fix typo in bungeecord arg parser and handle unknown arguments

configure.sh

@@ -23,7 +23,7 @@ function main {
           exit 1
         fi
         ;;
-      "benugeecord")
+      "bungeecord")
         bungeecord=true
         if $velocity || $standalone; then
           echo "argument bungeecord can't be used together with velocity or standalone"
@@ -43,6 +43,10 @@ function main {
       "--help")
         help=true
         ;;
+      *)
+        echo "Unknown argument: $arg"
+        exit 1
+        ;;
     esac
   done