"The Steam download did not finish" is the launcher's message for any
failed download, and what DepotDownloader said (the account does not own
the game, Steam refused the sign-in, the disk is full) was only written at
the debug level, so Open logs showed nothing to go on.
When a download fails, its last 40 lines are now written to the log as
warnings, after the exit code. The Steam login name is still left out, and
so are the rows of a QR code and the progress lines.