debug: fix debugees blocking when writing stderr

Fixes #98976

src/vs/workbench/contrib/debug/node/debugAdapter.ts

@@ -263,6 +263,8 @@ export class ExecutableDebugAdapter extends StreamDebugAdapter {
 						channel.append(sanitize(data));
 					}
 				});
+			} else {
+				this.serverProcess.stderr!.resume();
 			}
 
 			// finally connect to the DA