patch 9.0.2012: Vim9: error message can be more accurate

Problem:  Vim9: error message can be more accurate
Solution: Fix the error messages

Fix message for some single use error messages.

closes: #13312

Signed-off-by: Christian Brabandt <cb@256bit.org>
Co-authored-by: Ernie Rael <errael@raelity.com>
diff --git a/src/testdir/test_vim9_assign.vim b/src/testdir/test_vim9_assign.vim
index 07afadb..3a18777 100644
--- a/src/testdir/test_vim9_assign.vim
+++ b/src/testdir/test_vim9_assign.vim
@@ -1278,7 +1278,7 @@
     var n: any
     n.key = 5
   END
-  v9.CheckDefExecAndScriptFailure(lines, ['E1148:', 'E1203: Dot can only be used on a dictionary: n.key = 5'], 2)
+  v9.CheckDefExecAndScriptFailure(lines, ['E1148:', 'E1203: Dot not allowed after a number: n.key = 5'], 2)
 enddef
 
 def Test_assignment_local()