Use of SafeERC20 for known tokens used extra gas unnecessarily

[code423n4]

Handle

TomFrench

Vulnerability details

Impact

Increased gas costs

Proof of Concept

In a number of places we use the SafeERC20 library to transfer tokens which are fixed to a known implementation e.g Vader in the Converter.

https://github.com/code-423n4/2021-11-vader/blob/3a43059e33d549f03b021d6b417b7eeba66cf62e/contracts/tokens/converter/Converter.sol#L124

If we know that these tokens are properly implemented then we can do away with the extra cost from SafeERC20 and only use it when interacting with unknown tokens.

Recommended Mitigation Steps

Remove use of SafeERC20 for known good tokens.