Temperature determined as -1 with success status code

[lisabiermann]

For the temperatures determined via the false vacuum fraction it is possible that a success status code is reported but the temperature is -1. This is due to different conditions used for the stopping of the while loop and for the return of the temperature in BounceSolution::CalcTempAtFalseVacFraction.

Thanks to @cborschensky for bringing this to our attention!