serialisation of HRQNG is fixed so it would not make illegal reflective access on Java 17

src/net/torvald/terrarum/console/ScreencapNogui.kt

@@ -12,18 +12,19 @@ object ScreencapNogui: ConsoleCommand {
     override fun execute(args: Array<String>) {
         if (args.size == 2) {
             IngameRenderer.screencapExportCallback = {
-                val w = 960
-                val h = 640
-                val p = Pixmap.createFromFrameBuffer((it.width - w).ushr(1), (it.height - h).ushr(1), w, h)
+                val p = Pixmap.createFromFrameBuffer(0, 0, it.width, it.height)
                 PixmapIO2.writeTGA(Gdx.files.absolute(App.defaultDir + "/Exports/${args[1]}.tga"), p, true)
                 p.dispose()
             }
             IngameRenderer.screencapRequested = true
             Echo("FBO exported to$ccG Exports/${args[1]}.tga")
         }
+        else {
+            printUsage()
+        }
     }
 
     override fun printUsage() {
-
+        Echo("Usage: screencapnogui <output filename>")
     }
 }