Gracefully handle negative balances

[ms32035]

Pull Request

NautilusTrader prioritizes correctness and reliability, please follow existing patterns for validation and testing.

Summary

Under certain scenarios when running backtests with a margin account I would end up with a negative balance, which was then unhandled and caused:

  File "nautilus_trader/portfolio/portfolio.pyx", line 504, in nautilus_trader.portfolio.portfolio.Portfolio.update_order
  File "nautilus_trader/accounting/manager.pyx", line 145, in nautilus_trader.accounting.manager.AccountsManager.update_balances
  File "nautilus_trader/accounting/manager.pyx", line 473, in nautilus_trader.accounting.manager.AccountsManager._update_balance_single_currency
  File "nautilus_trader/model/objects.pyx", line 1631, in nautilus_trader.model.objects.AccountBalance.__init__
  File "nautilus_trader/core/correctness.pyx", line 57, in nautilus_trader.core.correctness.Condition.is_true
ValueError: `total` amount was negative

This PR handles the problems by properly raising AccountBalanceNegative

Related Issues/PRs

Type of change

• Bug fix (non-breaking)
• New feature (non-breaking)
• Breaking change (impacts existing behavior)
• Documentation update
• Maintenance / chore

Breaking change details (if applicable)

Release notes

• I added a concise entry to RELEASES.md that follows the existing conventions (when applicable)

Testing

Ensure new or changed logic is covered by tests.

• Affected code paths are already covered by the test suite
• I added/updated tests to cover new or changed logic

[CLAassistant]

All committers have signed the CLA.

[cjdsellers]

Hi @ms32035

Thanks for the contribution! I think this makes the negative balance condition much clearer.