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_textprop.vim b/src/testdir/test_textprop.vim
index 7a2fcf6..34fa6c9 100644
--- a/src/testdir/test_textprop.vim
+++ b/src/testdir/test_textprop.vim
@@ -1679,14 +1679,14 @@
 func Test_prop_func_invalid_args()
   call assert_fails('call prop_clear(1, 2, [])', 'E715:')
   call assert_fails('call prop_clear(-1, 2)', 'E16:')
-  call assert_fails('call prop_find(test_null_dict())', 'E715:')
+  call assert_fails('call prop_find(test_null_dict())', 'E1297:')
   call assert_fails('call prop_find({"bufnr" : []})', 'E730:')
   call assert_fails('call prop_find({})', 'E968:')
   call assert_fails('call prop_find({}, "x")', 'E474:')
   call assert_fails('call prop_find({"lnum" : -2})', 'E16:')
-  call assert_fails('call prop_list(1, [])', 'E715:')
+  call assert_fails('call prop_list(1, [])', 'E1206:')
   call assert_fails('call prop_list(-1, {})', 'E16:')
-  call assert_fails('call prop_remove([])', 'E474:')
+  call assert_fails('call prop_remove([])', 'E1206:')
   call assert_fails('call prop_remove({}, -2)', 'E16:')
   call assert_fails('call prop_remove({})', 'E968:')
   call assert_fails('call prop_type_add([], {})', 'E730:')
@@ -1699,7 +1699,7 @@
   call assert_fails("call prop_type_add('yyy', 'not_a_dict')", 'E715:')
   call assert_fails("call prop_add(1, 5, {'type':'missing_type', 'length':1})", 'E971:')
   call assert_fails("call prop_add(1, 5, {'type': ''})", 'E971:')
-  call assert_fails('call prop_add(1, 1, 0)', 'E715:')
+  call assert_fails('call prop_add(1, 1, 0)', 'E1206:')
 
   new
   call setline(1, ['first', 'second'])