"d. something" is not the only offender. I suspect it's a badly written parser. "m. anything" also breaks. And for fun, without the following word ("something"), the tweet just vanishes with no error at all.

I tried all of the non-space non-alphanumeric characters on my keyboard. Some worked, most caused an error.

d` d~ d$ d% d^ d& d( d) d- d+ d[ d] d{ d} d| d; d' d" d, d< d. d> d/ d?