Audit feedback

[jacque006]

What is this PR doing?

Integrating audit feedback into main.
Some of these changes have already been approved in #115

How can these changes be manually tested?

cd ./contracts
yarn hardhat test

Does this PR resolve or contribute to any issues?

No

Checklist

• I have manually tested these changes
• Post a link to the PR in the group chat

Guidelines

• If your PR is not ready, mark it as a draft
• The resolve conversation button is for reviewers, not authors
  • (But add a 'done' comment or similar)

[jacque006]

I cannot approve my own PR, but given that all of these commits are @jzaki & @voltrevo 's and some have been reviewed in other PRs I feel ok to merge in. I ensured contract tests passed and that I did not see any other issues when reviewing the diff.