ptyfwd-tool: don't segfault if called without arguments

src/ptyfwd/ptyfwd-tool.c

@@ -108,6 +108,9 @@ static int parse_argv(int argc, char *argv[]) {
                         assert_not_reached();
                 }
 
+        if (optind >= argc)
+                return log_error_errno(SYNTHETIC_ERRNO(EINVAL), "Expected command line, refusing.");
+
         return 1;
 }
 
@@ -156,6 +159,8 @@ static int run(int argc, char *argv[]) {
         if (!l)
                 return log_oom();
 
+        assert_se(!strv_isempty(l));
+
         r = sd_event_default(&event);
         if (r < 0)
                 return log_error_errno(r, "Failed to get event loop: %m");