ToME: the Tales of Maj'Eyal

Loading character savefile from main menu in game proceeds okay until it reaches 96% (on the loading bar) and then freezes. Neither any further mouse click or ESC key press works.
A Force Quit seems to be the only next thing to do.
I'm playing ToME: Tales of Maj'Eyal v1.5.5 on an Apple iMac desktop computer running OS X Yosemite Version 10.10.5

Here is the error log file:

error = "Lua Error: /mod/class/Game.lua:1285: attempt to index field 'party' (a nil value)\
At [C]:-1 __index\
At /mod/class/Game.lua:1285 getPlayer\
At /engine/Savefile.lua:784 md5Check\
At /engine/Savefile.lua:546 loadGame\
At /engine/Module.lua:1049 instanciate\
At /engine/utils.lua:2243 showMainMenu\
At /engine/init.lua:172 \
At [C]:-1 dofile\
At /loader/init.lua:217 "
seen = true
reported = false

Hoping the savefile can be rescued...?

_________________
" It is said that Crazy Horse had the power to dream himself into the real world...
...and leave the illusion behind! "