patch 8.2.1022: various parts of code not covered by tests

Problem:    Various parts of code not covered by tests.
Solution:   Add more tests. (Yegappan Lakshmanan, closes #6300)
diff --git a/src/testdir/test_blob.vim b/src/testdir/test_blob.vim
index 46b7b02..69b3504 100644
--- a/src/testdir/test_blob.vim
+++ b/src/testdir/test_blob.vim
@@ -254,6 +254,7 @@
   call assert_fails("call remove(b, 3, 2)", 'E979:')
   call assert_fails("call remove(1, 0)", 'E896:')
   call assert_fails("call remove(b, b)", 'E974:')
+  call assert_fails("call remove(b, 1, [])", 'E745:')
   call assert_fails("call remove(test_null_blob(), 1, 2)", 'E979:')
 endfunc