Image Does Not Exist errors are Runtime errors because DB has no way of knowing that an image/object/sound does not exist until the program is running and it tries to load it.
Most Runtime errors are reported by DB when they are caught, which in the case of programs that use Sync On, are at the line at which you do the Sync command (when the screen is being updated).
To find the correct line number of the error, simply change Sync ON to Sync OFF in your program and run it again.
With Sync Off, DB should report back the correct line number +1.
If you are using Dark Edit or the DB built-in editor, it says the error line is 1 higher than it actually is, so you just look at the preceding line. (I've been testing this out quite extensively for my DB Classic IDE just recently so it goes to the correct line when there's an error)
As such, with Sync On, errors usually stop on the line just before a Sync command which can be confusing.
TDK_Man