Crash reproduced on OS X 10.7.5, using a custom icons.svg file in ~/.config/inkscape/icons (based on the symbolic_icons.svg file), as well as with a copy of the tango_icons.svg file which is distributed with Inkscape.
Crash not reproduced with yet another custom icon file (not distributed with Inkscape).
Crash reproduced on OS X 10.7.5, using a custom icons.svg file in ~/.config/ inkscape/ icons (based on the symbolic_icons.svg file), as well as with a copy of the tango_icons.svg file which is distributed with Inkscape.
Crash not reproduced with yet another custom icon file (not distributed with Inkscape).