I'm running things on a raspberry Pi 3B. I don't have /tmp mounted as tmpfs, but regularly use tmpfs mounts for other purposes
I would suggest to increase the size of /tmp
you can do this by editing /etc/fstab, using sudo nano /etc/fstab
you should see a line, something like:
tmpfs /tmp tmpfs nodev,nosuid,size=2M 0 0
change 2M into 8M or whatever size you want (if you can spare the memory).
walk the file, using the arrows until the cursor is on the M after the 2, press backspace and press 8
now save the file, by pressing <CTRL>o, press the <ENTER> key and press <CTRL>x
the editor will now close.
reboot your system
df -h should now show a size of 8.0M
try again to see if that resolves the space problem
good luck
edit
you can verify how much memory you can spare with free -m
you already have 3 x 489M of tmpfs mounts
/edit
edit2
checked again, /tmp isn't mounted by default on raspbian
you, or some software you installed, changed that
you should simply remove the tmpfs entry for /tmp from your /etc/fstab
the other big entries, as I indicated earlier (489M) are also mounted as tmpfs on my system, be it different (smaller) in size
/edit2