ok but the savegame is still fucked up, because it will not be updated, maybe you can add a button like "remove missing block and continue".
i assume if i click yes the savegame will be updated and missing mod "forgot", but if i click yes and continue to play all i do from this moment will be missed and i'll stuck at the savepoint, pretty like the savegame becomes read-only
after checking better the console log i found those lines at the save point
2013-07-06 20:15:45 [iNFO] [Minecraft-Server] Saving chunks for level 'New World'/Overworld
2013-07-06 20:15:45 [WARNING] [Minecraft-Server] The save is being accessed from another location, aborting
and it happen everytime i remove a mod in every savegame, i need to start a new game, and the old one is locked since the modpack are restored like it was in the savegame.
i can press yes many time i want but forge still continue to warn me and asking what to do and not save with that error