Steps to reproduce:

1. Create "Discovery rule"
2. Add item prototype and type lld macro in "Update interval" or in "History storage period"
3. LLD macro should not be valid for update interval, for example / or 1.
4. Run LLD
5. Go to host->items list page

Result:
Undefined offset: 0 [items.php:1658 ? timeUnitToSeconds() in include/func.inc.php:801]
Expected:
no error on page

Also in this case in discovered item form in "Update interval" displayed default value (30s), but should be expanded LLD macro?