Ensure that ANSI is available

exec/syncterm-bounce.js

+require("userdefs.js", "USER_ANSI");
+
 function w(str)
 {
 	console.write(str);
@@ -196,6 +198,9 @@ function pixel_capability()
 	return ret;
 }
 
+if (!console.term_supports(USER_ANSI))
+	exit(0);
+
 if (console.cterm_version < 1316) {
 	console.pause();
 }