When starting Simutrans with sound turned off (using the -nosound command line flag), sound_desc_t::get_sound_id tries to load the sound anyway. This patch fixes the bug.
It was allowed to turn on sound via the dialog panel, even if started with -nosound. (same for nomidi). That was a change 8 years ago.
As a player, I am surprised to read that. I do not want Simutrans to load sound files when the -nosound parameter is used. When the pakset and/or savegame are so large that I am running low on RAM, it is very useful to be able to skip loading sound files.
You can rename the sound folder ... But the sound fiels are tiny compared to the images in memory.