patch 8.2.0644: insufficient testing for invalid function arguments

Problem:    Insufficient testing for invalid function arguments.
Solution:   Add more tests. (Yegappan Lakshmanan, closes #5988)
diff --git a/src/testdir/test_match.vim b/src/testdir/test_match.vim
index cd8ae2e..fca646d 100644
--- a/src/testdir/test_match.vim
+++ b/src/testdir/test_match.vim
@@ -163,6 +163,7 @@
   call assert_fails("call matchadd('Search', 'XXX', 1, 123, 1)", 'E715:')
   call assert_fails("call matchadd('Error', 'XXX', 1, 3)", 'E798:')
   call assert_fails("call matchadd('Error', 'XXX', 1, 0)", 'E799:')
+  call assert_fails("call matchadd('Error', 'XXX', [], 0)", 'E745:')
 endfunc
 
 func Test_matchaddpos()
@@ -278,6 +279,8 @@
   call assert_fails("call matchaddpos('Error', [1], 1, 5, {'window':12345})", 'E957:')
   " Why doesn't the following error have an error code E...?
   call assert_fails("call matchaddpos('Error', [{}])", 'E290:')
+  call assert_equal(-1, matchaddpos('Error', test_null_list()))
+  call assert_fails("call matchaddpos('Error', [1], [], 1)", 'E745:')
 endfunc
 
 func OtherWindowCommon()
@@ -334,5 +337,4 @@
   call delete('XscriptMatchCommon')
 endfunc
 
-
 " vim: shiftwidth=2 sts=2 expandtab