Files sometimes disappear from Tor Browser folder during downloading but continue downloading

Before the file disappears from the Tor Browser folder Tails sometimes freezes for a short moment.
Then the file is gone from the Tor Browser folder but the download continues and the necessary space keeps getting allocated.
The download will fail at the end but the space is not freed and it can fill up your (ram?) disk until it is full and a reboot is required.

When it happened once it seems to be more likely to happen again during this Tails session.
It happens roughly 1 out of 100 downloads (<-- guesstimation) and i can not reliably reproduce it.