[restored issue] - draw_hqr: handle exception when directory not writable
$ /usr/bin/draw_hqr
zsh: segmentation fault /usr/bin/draw_hqr
openat(AT_FDCWD, "tphqr.svg", O_RDWR|O_CREAT|O_TRUNC, 0666) = -1 EACCES (Permission non accordée)
suggestion: throw an error instead of segfault when directory is not writable.
Issue raised by Sam Thibault.
Warning: this issue has been restored from backup and can have been changed. For example, all comments have been lost.