patch 9.0.0335: checks for Dictionary argument often give a vague error

Problem:    Checks for Dictionary argument often give a vague error message.
Solution:   Give a useful error message. (Yegappan Lakshmanan, closes #11009)
diff --git a/src/testdir/test_listdict.vim b/src/testdir/test_listdict.vim
index 89c4243..154aa98 100644
--- a/src/testdir/test_listdict.vim
+++ b/src/testdir/test_listdict.vim
@@ -981,7 +981,7 @@
 
   call assert_fails('call reverse("")', 'E899:')
   call assert_fails('call uniq([1, 2], {x, y -> []})', 'E745:')
-  call assert_fails("call sort([1, 2], function('min'), 1)", "E715:")
+  call assert_fails("call sort([1, 2], function('min'), 1)", "E1206:")
   call assert_fails("call sort([1, 2], function('invalid_func'))", "E700:")
   call assert_fails("call sort([1, 2], function('min'))", "E118:")