If the storage.used increasing during the withdraw, the bridging transaction will be broken.

[btspoony]

Instructions

Bridge a NFT or FT which storage.used will be increated during the withdrawal.

Problem

The bridging to evm transaction will be in a error.

Steps to Reproduce

Transaction Sample: https://www.flowdiver.io/tx/0e84fe1f20b56b025647bf55135a38fdea40f371172128e2fc46d019c949b95f?tab=script

Panic line: https://github.com/onflow/flow-evm-bridge/blob/main/cadence/transactions/bridge/tokens/bridge_tokens_to_evm.cdc#L67

All Fixes FT will have a chance to add metadata to Vault during withdraw, so the storage.used will be increased.

Acceptance Criteria

Not to panic

Context

[sisyphusSmiling]

Thanks for reporting. Yeah, we'll need to cover underflow in this case though it's not clear how the fee will be estimated in this case. The bridge has to charge fees based on storage consumption so there's a chance that the transaction will revert on withdrawing the fee from the scoped provider. I'll look into this

[bluesign]

passing function for fee is one option. something like:

self.coa.depositTokens(
            vault: <-self.sentVault,
            feeProviderFunc: fun(amount: UFix64):@{FungibleToken.Vault}{
            //here you can assert fee and decide to bridge or not 
           ....
            }
)