Add zero address check for sender

[smol-ninja]

There is no check if the sender is a zero address.

Anybody can accidentally set sender as zero address when creating the streams. Now because other functions such as cancel, renounce etc. are sender only, the stream creator would not be able to use them.

Thus, the task is to add zero address check for sender.

References

• Remove zero address check for sender flow#198
• Are address(0) checks worth it for msg.sender and similar? #38 (comment)

[PaulRBerg]

Agree with the general point, however:

it can lead to denial-of-service with those functionalities

That doesn't sound correct. Why would it be DoS?

[smol-ninja]

Yeah you're right. I was talking in the context of genuine creator who accidentally used zero address for sender. And this would lead him to not be able to use services (cancel, renounce etc). But I think I misused "denial-of-service" in the description (edited now).

[PaulRBerg]

Got it, thanks for explaining.