patch 8.2.0642: Vim9: using invalid index

Problem:    Vim9: using invalid index.
Solution:   Check index for being valid.  Fix memory leak.
diff --git a/src/clientserver.c b/src/clientserver.c
index 5245425..cf35c81 100644
--- a/src/clientserver.c
+++ b/src/clientserver.c
@@ -473,6 +473,7 @@
 # ifdef FEAT_GUI_MSWIN
 		Shell_NotifyIcon(NIM_DELETE, &ni);
 # endif
+		vim_free(done);
 	    }
 	}
 	else if (STRICMP(argv[i], "--remote-expr") == 0)