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

[solnic]

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

[whatyouhide]

Since this is for an older Elixir version that we will eventually (maybe soon enough) drop, we can leave out the testing and just ship the fix IMO.

Include label info in the report too in metadata?

Nah it's fine not to. Basically, as soon as CI passes I think this PR is ready to go.

[solnic]

@whatyouhide alright, so it's ready to go, just need a ✅ 😄