patch 9.0.0345: error message for list argument could be clearer

Problem:    Error message for list argument could be clearer.
Solution:   Include the argument number. (Yegappan Lakshmanan, closes #11027)
diff --git a/src/testdir/test_utf8.vim b/src/testdir/test_utf8.vim
index 862e73b..bb99cb3 100644
--- a/src/testdir/test_utf8.vim
+++ b/src/testdir/test_utf8.vim
@@ -168,7 +168,7 @@
 
   call setcellwidths([])
 
-  call assert_fails('call setcellwidths(1)', 'E714:')
+  call assert_fails('call setcellwidths(1)', 'E1211:')
 
   call assert_fails('call setcellwidths([1, 2, 0])', 'E1109:')