Well,
flexicontent module broken ?
in what way ?
maybe with some configuration a bug can appear , but it is not broken
Did you try to install FLEXIcontent on clean site and test both the given code and the module?
Also note, that i have just now tested (again in both J1.5 and J2.5) the code providen in documentation and it works (also made a small update for item model name to be correct for J2.5 as it is different than in J1.5)
maybe there is another reason for it to crash