Submitted by gjaldon, also found by Aymen0909, 0x52, hansfriese, KIntern_NA, and rvierdiiev
https://github.com/code-423n4/2023-01-popcorn/blob/main/src/vault/VaultController.sol#L443-L471 
https://github.com/code-423n4/2023-01-popcorn/blob/main/src/utils/MultiRewardStaking.sol#L265-L270 
https://github.com/code-423n4/2023-01-popcorn/blob/main/src/utils/MultiRewardStaking.sol#L178-L179 
https://github.com/code-423n4/2023-01-popcorn/blob/main/src/utils/MultiRewardStaking.sol#L201 
https://github.com/code-423n4/2023-01-popcorn/blob/main/src/utils/MultiRewardEscrow.sol#L97-L98
When a Vault owner creates/adds a reward token to the Staking contract with faulty escrow config parameters, the reward tokens sent to the Staking contract will forever be locked up. This can happen since there are no validity checks on the values of the Escrow config for the reward tokens when adding a reward token to the Staking contract via the VaultController.
Below are the steps to reproduce the issue:
VS Code
  Make sure that escrowDuration is greater than 0 and that escrowPercentage is high enough that it wont always trigger reverts when users claim rewards.
RedVeil (Popcorn) confirmed 
