It seems like $this->today->year...this->birth->year can also be of type double. However, the property $age is declared as type integer. Added an additional type check

Signed-off-by: Fabien Crassat <fabien@crassat.com>
Refactoring of HumanFileName

Signed-off-by: Fabien Crassat <fabien@crassat.com>