Remove unnecessary null pointer checks

[elfring]

An extra null pointer check is not needed like in the macros "DELETE" and "DELETEA".

[Harha]

Thanks for this! I will delete those checks. I have no idea why I haven't realized this any earlier, can't really remember where I got that idea of checking for null before delete.

[elfring]

Would it be better to keep this issue open until it will be fixed anyhow?