Flaky test in `MockERC20YearnVault`: `Expected "1000000099991" to be equal 1000000099996`

[cameel]

I'm seeing one of the tests fail from time to time. It doesn't always happen but does often enough to be noticeable. I've seen at least 6 cases in the last few days: 957293, 955718, 954761, 954426, 954379, 954343.

I can't exclude the possibility that it's actually caused by something in the compiler (the way I run it, I'm forcing your code to run with latest solc) or in the way I run it but since it happens only occasionally, some slight non-determinism in JS test logic seems more likely to me.

Failing test output

 154 passing (5m)
  1 failing

  1) MockERC20YearnVault
       deposit - withdraw with rewards unlock
         correctly handles deposits and withdrawals:

      AssertionError: Expected "1000000099991" to be equal 1000000099996
      + expected - actual

       {
      -  "_hex": "0xe8d4a6969c"
      +  "_hex": "0xe8d4a69697"
         "_isBigNumber": true
       }
      
      at Context.<anonymous> (test/mockERC20YearnVaultTest.ts:183:58)
      at runMicrotasks (<anonymous>)
      at processTicksAndRejections (node:internal/process/task_queues:96:5)
      at runNextTicks (node:internal/process/task_queues:65:3)
      at listOnTimeout (node:internal/timers:526:9)
      at processTimers (node:internal/timers:500:7)