installed ejabberd от FreeBSD then install mod_log_chat (ejabberdctl modules_update_specs -> ejabberdctl module_install mod_log_chat) and see error when starting ejabberd:
[error] Supervisor ejabberd_sup had child ejabberd_gen_mod_sup started with gen_mod:start_link() at undefined exit with reason {'EXIT',{undef,[{econf,any,[],[]},{mod_log_chat,mod_opt_type,1,[{file,"/root/.ejabberd-modules/sources/ejabberd-contrib/mod_log_chat/src/mod_log_chat.erl"},{line,282}]},{gen_mod,'-get_validators/2-fun-1-',3,[{file,"src/gen_mod.erl"},{line,512}]},{lists,foldl,3,[{file,"lists.erl"},{line,1263}]},{gen_mod,get_validators,2,[{file,"src/gen_mod.erl"},{line,499}]},{gen_mod,validate_opts,3,[{file,"src/gen_mod.erl"},{line,557}]},{gen_mod,start_module,5,[{file,"src/gen_mod.erl"},{line,209}]},{lists,foreach,...}]}} in context start_error 02:36:32.939 [critical] Failed to start ejabberd application: {error,{shutdown,{failed_to_start_child,ejabberd_gen_mod_sup,{'EXIT',{undef,[{econf,any,[],[]},{mod_log_chat,mod_opt_type,1,[{file,"/root/.ejabberd-modules/sources/ejabberd-contrib/mod_log_chat/src/mod_log_chat.erl"},{line,282}]},{gen_mod,'-get_validators/2-fun-1-',3,[{file,"src/gen_mod.erl"},{line,512}]},{lists,foldl,3,[{file,"lists.erl"},{line,1263}]},{gen_mod,get_validators,2,[{file,"src/gen_mod.erl"},{line,499}]},{gen_mod,validate_opts,3,[{file,"src/gen_mod.erl"},{line,557}]},{gen_mod,start_module,5,[{file,"src/gen_mod.erl"},{line,209}]},{lists,foreach,2,[{file,"lists.erl"},{line,1338}]}]}}}}}