Impact

The collectProtocolRevenue function lacks a zero address validation check for the to parameter. This could lead to permanent loss of protocol revenue if an admin accidentally provides address(0) as the destination address.

If the admin mistakenly passes address(0) as the to parameter:

1. The function will execute without reverting

2. The protocol revenue will be reduced to 0: protocolRevenue[token] = 0

3. The tokens will be transferred to the zero address

4. These tokens will be permanently lost as the zero address is inaccessible

https://github.com/Cyfrin/2024-10-sablier/blob/8a2eac7a916080f2022527408b004578b21c51d0/src/abstracts/SablierFlowBase.sol#L207

Recommendations

Add a zero address validation check at the beginning of the function