patch 8.2.3238: Vim9: error message does not indicate the location

Problem:    Vim9: error message does not indicate the location.
Solution:   Add the relevant text. (issue #8634)
diff --git a/src/testdir/test_vim9_expr.vim b/src/testdir/test_vim9_expr.vim
index 88f725b..f207056 100644
--- a/src/testdir/test_vim9_expr.vim
+++ b/src/testdir/test_vim9_expr.vim
@@ -3114,7 +3114,7 @@
   call CheckDefExecAndScriptFailure(["var x = +g:alist"], 'E745:', 1)
   call CheckDefExecAndScriptFailure(["var x = +g:adict"], 'E728:', 1)
 
-  call CheckDefAndScriptFailure2(["var x = ''", "var y = x.memb"], 'E715:', 'E488:', 2)
+  call CheckDefAndScriptFailure2(["var x = ''", "var y = x.memb"], 'E1229: Expected dictionary for using key "memb", but got string', 'E488:', 2)
 
   call CheckDefAndScriptFailure2(["'yes'->", "Echo()"], 'E488: Trailing characters: ->', 'E260: Missing name after ->', 1)