Check if the start time is in the future in linear contract

[andreivladbrg]

Now, since cliff time can be zero, this check is not enough in SablierV2LockupLinear._calculateStreamedAmount:

v2-core/src/SablierV2LockupLinear.sol

Lines 191 to 195 in cf246ef

	uint256 cliffTime = uint256(_cliffs[streamId]);
	uint256 blockTimestamp = block.timestamp;
	if (cliffTime > blockTimestamp) {
	return 0;
	}

Test to run

It will revert with a PRB Math error since we use unchecked: https://app.warp.dev/block/OBorEzMLUvWOk9R8CmXlky

    function test_Cancel_Pending_Linear() public {
        vm.warp({ newTimestamp: defaults.START_TIME() - 100 });

        LockupLinear.Timestamps memory timestamps = defaults.lockupLinearTimestamps();
        timestamps.cliff = 0;

        uint256 streamId = createDefaultStreamWithTimestamps(timestamps);

        console2.log("Stream ID: %d status is %d", streamId, uint8(lockup.statusOf(streamId)));

        lockup.cancel(streamId);
    }

Thus, we should also check if the start time is in the future.

Also, ref of the issue here.

[PaulRBerg]

It is worth noting that this bug does not affect any Sablier contract running in production, since we haven't deployed V2.2 yet.