So, before to run the glm(), please
data$alcohol_safe[data$alcohol_safe == "NA"] <- 0.0
You can assign in your criteria, what value to replace these NA´s, in my case I use to asign 0 or 0.0 as the last code. (0.0 to recognize which values were NA´s)
If your ploblem are NA´s, sometimes we must use a critical thinking or criteria in these values, and sometimes you have to replace these for zero values.
I hope this helps, let´s change NA´s values with that code and try again