wtw node's treat_current_input method can produce a division by 0

[RobinMaesPrior]

Suggested work around is:

denominator = self.liquor["volume"] + influent["volume"] * self.liquor_multiplier["volume"]
if denominator != 0:
    self.liquor[key] = (
        self.liquor[key] * self.liquor["volume"]
        + influent[key] * influent["volume"] * self.liquor_multiplier["volume"]
    ) / denominator
else:
    # Handle the case where the denominator is zero
    self.liquor[key] = 0  # or some other default value