From f7aba76f638a00b1a7c86448bf3f90b69b6eb56d Mon Sep 17 00:00:00 2001
From: Blake Kostner <git@btkostner.io>
Date: Tue, 8 Aug 2023 13:47:24 -0600
Subject: [PATCH] fix: add additional protective wrapping to crash log handling
 (#5)

---
 lib/logger_json/formatters/datadog_logger.ex  | 16 +++++++++++++-
 .../formatters/datadog_logger_test.exs        | 21 +++++++++++++++++++
 2 files changed, 36 insertions(+), 1 deletion(-)

diff --git a/lib/logger_json/formatters/datadog_logger.ex b/lib/logger_json/formatters/datadog_logger.ex
index 0f84fce..435e773 100644
--- a/lib/logger_json/formatters/datadog_logger.ex
+++ b/lib/logger_json/formatters/datadog_logger.ex
@@ -120,7 +120,7 @@ defmodule LoggerJSON.Formatters.DatadogLogger do
   # errors to automatically be aggregated by error tracking.
   defp format_process_crash(metadata) do
     case Keyword.get(metadata, :crash_reason) do
-      {reason, stacktrace} ->
+      {reason, stacktrace} when is_list(stacktrace) ->
         initial_call = Keyword.get(metadata, :initial_call)
 
         json_map(
@@ -130,6 +130,20 @@ defmodule LoggerJSON.Formatters.DatadogLogger do
           kind: format_exception_kind(reason)
         )
 
+      # This should never happen unless you are manually faking
+      # a crash reason. Non the less, we've had errors appear
+      # in the past where `Exception.format_stacktrace/1` has
+      # not received a list of stacktrace entries.
+      {reason, not_a_stacktrace} ->
+        initial_call = Keyword.get(metadata, :initial_call)
+
+        json_map(
+          initial_call: format_initial_call(initial_call),
+          stack: inspect(not_a_stacktrace),
+          message: format_exception_message(reason),
+          kind: format_exception_kind(reason)
+        )
+
       nil ->
         nil
     end
diff --git a/test/unit/logger_json/formatters/datadog_logger_test.exs b/test/unit/logger_json/formatters/datadog_logger_test.exs
index acc109b..877447d 100644
--- a/test/unit/logger_json/formatters/datadog_logger_test.exs
+++ b/test/unit/logger_json/formatters/datadog_logger_test.exs
@@ -435,6 +435,27 @@ defmodule LoggerJSONDatadogTest do
     assert log["error"]["stack"] =~ "stacktrace test"
   end
 
+  test "inspects any non stacktrace crash reason data" do
+    Logger.configure_backend(LoggerJSON, metadata: [:crash_reason])
+
+    Logger.metadata(
+      crash_reason: {
+        :exit,
+        {Task.Supervised, :stream, [5000]}
+      }
+    )
+
+    log =
+      fn -> Logger.debug("hello") end
+      |> capture_log()
+      |> Jason.decode!()
+
+    assert is_nil(log["error"]["initial_call"])
+    assert log["error"]["kind"] == "exit"
+    assert log["error"]["message"] == "exit"
+    assert log["error"]["stack"] =~ "{Task.Supervised, :stream, [5000]}"
+  end
+
   test "logs erlang style crash reasons" do
     Logger.configure_backend(LoggerJSON, metadata: [:crash_reason])
     Logger.metadata(crash_reason: {:socket_closed_unexpectedly, []})