[MoM] Check for beta talker on damage EoCs

[Standing-Storm]

Summary

Bugfixes "[MoM] Check for beta talker on damage EoCs"

Purpose of change

The monster_takes_damage EoCs also trigger if the monster suffers damage with no source (like the unviable portal life forms). If the damage has no source, they have no attacker, and the EoC checking the attacker for conditions fails to find anything, causing a talker error.

Fixes #77085

Describe the solution

Make the first condition has_beta and only check effects on the beta talker if there is a beta talker to check effects on.

Describe alternatives you've considered

Testing

Cannot load the provided save, but spawned in an alien meadow and waited for 20 hours while veiled butterflies flew around. No crashes.

Additional context

Sukkot starts tonight at sundown straight into Shabbat so it's going to be a few days until I can make sure this actually works.