patch 9.0.1138: crash when expecting varargs but it is something else

Problem:    Crash when expecting varargs but it is something else.
Solution:   Only use the member when the type is a list. (closes #11774)
diff --git a/src/testdir/test_vim9_func.vim b/src/testdir/test_vim9_func.vim
index be07aec..bf8b705 100644
--- a/src/testdir/test_vim9_func.vim
+++ b/src/testdir/test_vim9_func.vim
Binary files differ