darktable database lock file seems to be empty

[init] the database lock file seems to be empty
[init] database is locked, probably another process is already using it
trying to open the images in the running instance

<LebedevRI> just remove ~/.config/darktable/library.db.lock, it's safe
$ rm ~/.config/darktable/library.db.lock

<LebedevRI> also data.db.lock
$ rm ~/.config/darktable/data.db.lock