Not fixed, 0 damage beams still kill astronauts.
However, I did notice something, I think the 1st tick does no astronaut damage but the rest does?
It's also that the piercing damage of beams kills the astronaut but hard to see that, there shouldn't be any to begin with since it's just 1 entity you hit and not multiple blocks.
Tried putting the default beam on a single tick per burst. 1st burst and the astronaut didn't receive damage/didn't die. Second burst though and he died immediately.