ZeroDivisionError: float division by zero

[sentry-io]

Sentry Issue: SENTRY-3KJB

ZeroDivisionError: float division by zero
  File "sentry/dynamic_sampling/models/common.py", line 28, in guarded_run
    return model.run(model_input)
  File "sentry/dynamic_sampling/models/base.py", line 38, in run
    return self._run(model_input)
  File "sentry/dynamic_sampling/models/transactions_rebalancing.py", line 133, in _run
    implicit_rate = implicit_budget / total_implicit

[constantinius]

This is actually two issues in disguise:
1. when no transactions/classes are passed in (sentry/dynamic_sampling/models/transactions_rebalancing.py in _run at line 133)
2. when transactions/classes are passed, but the total count is equal to the total explicit count, resulting in the total_implicit to be 0, thus resulting in the ZeroDivisionError (sentry/dynamic_sampling/models/transactions_rebalancing.py in _run at line 110)