patch 8.2.1888: Vim9: getbufline(-1, 1, '$') gives an error

Problem:    Vim9: Getbufline(-1, 1, '$') gives an error.
Solution:   Return an empty list. (closes #7180)
diff --git a/src/testdir/test_vim9_builtin.vim b/src/testdir/test_vim9_builtin.vim
index e3d7bb6..d6891a8 100644
--- a/src/testdir/test_vim9_builtin.vim
+++ b/src/testdir/test_vim9_builtin.vim
@@ -242,6 +242,8 @@
   var lines = ['aaa', 'bbb', 'ccc']
   setbufline(buf, 1, lines)
   getbufline('#', 1, '$')->assert_equal(lines)
+  getbufline(-1, '$', '$')->assert_equal([])
+  getbufline(-1, 1, '$')->assert_equal([])
 
   bwipe!
 enddef