Use _safeMint() instead of _mint()

[code423n4]

Lines of code

https://github.com/PartyDAO/party-contracts-c4/blob/3896577b8f0fa16cba129dc2867aba786b730c1b/contracts/crowdfund/Crowdfund.sol#L439
https://github.com/PartyDAO/party-contracts-c4/blob/3896577b8f0fa16cba129dc2867aba786b730c1b/contracts/crowdfund/Crowdfund.sol#L480

Vulnerability details

Impact

OpenZeppelin recommends the usage of _safeMint() instead of _mint(). If the recipient is a contract, safeMint() checks whether they can handle ERC721 tokens.

Proof of Concept

If the user provides an address that can't handle ERC721 tokens when calling contribute() to CrowdFund the minted token might be lost. That would also result in the user not being able to do any governance action (vote, delegate) on Party

contribute() callable by a user:

https://github.com/PartyDAO/party-contracts-c4/blob/3896577b8f0fa16cba129dc2867aba786b730c1b/contracts/crowdfund/Crowdfund.sol#L191

Resulting in the following _mint() call:

https://github.com/PartyDAO/party-contracts-c4/blob/3896577b8f0fa16cba129dc2867aba786b730c1b/contracts/crowdfund/Crowdfund.sol#L439

And when CrowdFund token is burnt, it called _mint() on PartyGovernance
https://github.com/PartyDAO/party-contracts-c4/blob/3896577b8f0fa16cba129dc2867aba786b730c1b/contracts/crowdfund/Crowdfund.sol#L480

Tools Used

Manual Anaylsis

Recommended Mitigation Steps

Use _safeMint() whenever possible

[merklejerk]

Duplicate of #18

[HardlyDifficult]

Converting into a QA report for the warden.

[HardlyDifficult]

Merging with #311