How to fix *Bad argument in call to erlang:'++'(<<"xxx/crash.log">>, ".3") in lager_rotator_default:rotate_logfile/2 line 84*

Erlang/OTP 25 [erts-13.2.2] [source] [64-bit] [smp:8:8] [ds:8:8:10] [async-threads:1]

15:22:35.803 [error] gen_event {lager_file_backend,<<102,105,115,104,95,99,104,97,105,110,46,108,111,103>>} installed in lager_event terminated with reason: bad argument in call to erlang:'++'(<<"/var/log/xxx/xxx.log">>, ".198") in lager_rotator_default:rotate_logfile/2 line 84
15:22:35.803 [error] Lager event handler {lager_file_backend,<<"fish_chain.log">>} exited with reason {'EXIT',{badarg,[{erlang,'++',[<<"/var/log/xxx/xxx.log">>,".198"],[{error_info,#{module => erl_erts_errors}}]},{lager_rotator_default,rotate_logfile,2,[{file,"/home/gitlab-runner/builds/Zrpgky1W/0/justkey/fish/fish-serv/deps/lager/src/lager_rotator_default.erl"},{line,84}]},{lager_file_backend,write,4,[{file,"/home/gitlab-runner/builds/Zrpgky1W/0/justkey/fish/fish-serv/deps/lager/src/lager_file_backend.erl"},{line,253}]},{lager_file_backend,handle_event,2,[{file,"/home/gitlab-..."},...]},...]}}
15:22:35.804 [error] gen_server lager_crash_log terminated with reason: bad argument in call to erlang:'++'(<<"/var/log/xxx/crash.log">>, ".3") in lager_rotator_default:rotate_logfile/2 line 84
15:22:35.804 [error] CRASH REPORT Process lager_crash_log with 0 neighbours crashed with reason: bad argument in call to erlang:'++'(<<"/var/log/xxx/crash.log">>, ".3") in lager_rotator_default:rotate_logfile/2 line 84
15:22:35.804 [error] Supervisor lager_sup had child lager_crash_log started with lager_crash_log:start_link("crash.log", 65536, 10485760, [{hour,0}], 5, lager_rotator_default) at <0.3235.0> exit with reason bad argument in call to erlang:'++'(<<"/var/log/xxx/crash.log">>, ".3") in lager_rotator_default:rotate_logfile/2 line 84 in context child_terminated