No debugging unless the game is running

src/main.rs

@@ -3,7 +3,7 @@
 
 use std::{path::PathBuf, process, time::SystemTime};
 
-use anyhow::Result;
+use anyhow::{bail, Result};
 use app::Application;
 use clap::Parser;
 use emulator::EmulatorBuilder;
@@ -95,10 +95,13 @@ fn main() -> Result<()> {
     let args = Args::parse();
 
     let (mut builder, client) = EmulatorBuilder::new();
-    if let Some(path) = args.rom {
-        builder = builder.with_rom(&path);
+    if let Some(path) = &args.rom {
+        builder = builder.with_rom(path);
     }
     if args.debug_port.is_some() {
+        if args.rom.is_none() {
+            bail!("to start debugging, please select a game.");
+        }
         builder = builder.start_paused(true);
     }