patch 8.2.0644: insufficient testing for invalid function arguments

Problem:    Insufficient testing for invalid function arguments.
Solution:   Add more tests. (Yegappan Lakshmanan, closes #5988)
diff --git a/src/testdir/test_clientserver.vim b/src/testdir/test_clientserver.vim
index 4a48aed..152a2e1 100644
--- a/src/testdir/test_clientserver.vim
+++ b/src/testdir/test_clientserver.vim
@@ -164,6 +164,7 @@
     endif
   endtry
 
+  call assert_fails('call remote_startserver([])', 'E730:')
   call assert_fails("let x = remote_peek([])", 'E730:')
   call assert_fails("let x = remote_read('vim10')", 'E277:')
   call assert_fails("call server2client('abc', 'xyz')", 'E258:')