patch 8.2.2365: Vim9: no check for map() changing item type at script level

Problem:    Vim9: no check for map() changing item type at script level.
Solution:   Check the new value type.
diff --git a/src/testdir/test_vim9_assign.vim b/src/testdir/test_vim9_assign.vim
index 8dadb2c..c035558 100644
--- a/src/testdir/test_vim9_assign.vim
+++ b/src/testdir/test_vim9_assign.vim
@@ -1351,7 +1351,7 @@
       var ll: list<number>
       ll = [1, 2, 3]->map('"one"')
   END
-  CheckDefExecFailure(lines, 'E1012: Type mismatch; expected list<number> but got list<string>')
+  CheckDefExecFailure(lines, 'E1012: Type mismatch; expected number but got string')
 enddef
 
 def Test_cannot_use_let()