Fix log formatting under 1.14

[solnic]

I traced it down to being an Elixir < 1.15 issue. This is what log_unfiltered receives under 1.14 when system crashes internally:

%{
        label: {:proc_lib, :crash},
        report: [
          [
            initial_call: {Phoenix.LiveReloader.Channel, :join, [:Argument__1, :Argument__2, :Argument__3]},
            pid: "pid id",
            registered_name: [],
            error_info: {
              :error,
              %ArgumentError{message: "unknown registry: PhoenixApp.PubSub"},
              [
                {Registry, :info!, 1, [file: 'lib/registry.ex', line: 1373]},
                {Registry, :register, 3, [file: 'lib/registry.ex', line: 989]},
                {Phoenix.PubSub, :subscribe, 3, [file: 'lib/phoenix/pubsub.ex', line: 121]},
                {Phoenix.Channel.Server, :init_join, 3, [file: 'lib/phoenix/channel/server.ex', line: 434]},
                {Phoenix.Channel.Server, :channel_join, 4, [file: 'lib/phoenix/channel/server.ex', line: 396]},
                {Phoenix.Channel.Server, :handle_info, 2, [file: 'lib/phoenix/channel/server.ex', line: 305]},
                {:gen_server, :try_handle_info, 3, [file: 'gen_server.erl', line: 1095]},
                {:gen_server, :handle_msg, 6, [file: 'gen_server.erl', line: 1183]},
                {:proc_lib, :init_p_do_apply, 3, [file: 'proc_lib.erl', line: 241]}
              ]
            },
            ancestors: ["pid id", PhoenixAppWeb.Endpoint.Phoenix.LiveReloader.Socket, PhoenixAppWeb.Endpoint, PhoenixApp.Supervisor, "pid id"],
            message_queue_len: 0,
            messages: [],
            links: ["pid id"],
            dictionary: ["$callers": ["pid id"]],
            trap_exit: false,
            status: :running,
            heap_size: 17731,
            stack_size: 28,
            reductions: 15540
          ],
          []
        ]
      }

As a quick PoC I just updated log_unfiltered to match this and extract error_info to capture exception.

WITHOUT the fix, here's how it looked like:

Here's the result WITH the fix

TODO

• Make it work 🙃
• Somehow reproduce this in a test (any suggestions how?)
• Make it capture it only under Elixir older than 1.15
• Verify that it's the same with 1.13 actually
• Include label info in the report too in metadata?

[solnic]

@whatyouhide could you take a quick look? any idea how to reproduce this in a test?