Error starting under OTP 21 due to lager configuration

[aeden]

When starting erldns under OTP 21 using an erldns.config.example configuration and the run.sh script, erldns crashes with:

=CRASH REPORT==== 10-Sep-2018::09:47:06.215049 ===
  crasher:
    initial call: lager_handler_watcher:init/1
    pid: <0.113.0>
    registered_name: []
    exception exit: noproc
      in function  gen:do_for_proc/2 (gen.erl, line 228)
      in call from gen_event:rpc/2 (gen_event.erl, line 239)
      in call from lager_handler_watcher:install_handler2/3 (/Users/anthonyeden/d/dnsimple/erldns/_build/default/lib/lager/src/lager_handler_watcher.erl, line 117)
      in call from lager_handler_watcher:init/1 (/Users/anthonyeden/d/dnsimple/erldns/_build/default/lib/lager/src/lager_handler_watcher.erl, line 51)
      in call from gen_server:init_it/2 (gen_server.erl, line 374)
      in call from gen_server:init_it/6 (gen_server.erl, line 342)
    ancestors: [lager_handler_watcher_sup,lager_sup,<0.98.0>]
    message_queue_len: 0
    messages: []
    links: [<0.101.0>]
    dictionary: []
    trap_exit: false
    status: running
    heap_size: 987
    stack_size: 27
    reductions: 259
  neighbours:

[aeden]

Issue in erlang-rebar/lager: https://github.com/erlang-lager/lager/issues/452

[aeden]

As of Erlang/OTP 21.0, erlang now has its own logger interface. It may make sense to switch to that.