feat: bug in one reporter doesn't affect other reporters

lib/tower.ex

@@ -208,6 +208,14 @@ defmodule Tower do
   passed along to the reporter.
   """
 
+  defmodule ReportEventError do
+    defexception [:original_exception, :reporter]
+
+    def message(%__MODULE__{reporter: reporter}) do
+      "An error occurred while trying to report an event with reporter #{reporter}"
+    end
+  end
+
   alias Tower.Event
 
   @default_reporters [Tower.EphemeralReporter]
@@ -396,9 +404,23 @@ defmodule Tower do
   defp report_event(%Event{} = event) do
     reporters()
     |> Enum.each(fn reporter ->
-      async(fn ->
+      report_event(reporter, event)
+    end)
+  end
+
+  defp report_event(reporter, %Event{reason: %ReportEventError{reporter: reporter}}) do
+    # Ignore so we don't enter in a loop trying to report to the same buggy reporter
+    :ignore
+  end
+
+  defp report_event(reporter, event) do
+    async(fn ->
+      try do
         reporter.report_event(event)
-      end)
+      rescue
+        exception ->
+          raise ReportEventError, reporter: reporter, original_exception: exception
+      end
     end)
   end
 

test/tower_test.exs

@@ -470,6 +470,57 @@ defmodule TowerTest do
     assert is_list(stacktrace)
   end
 
+  test "bug in one reporter doesn't affect other reporters" do
+    defmodule BuggyReporter do
+      @behaviour Tower.Reporter
+
+      @impl true
+      def report_event(_event) do
+        raise "I have a bug"
+      end
+    end
+
+    put_env(:reporters, [BuggyReporter, Tower.EphemeralReporter])
+
+    capture_log(fn ->
+      in_unlinked_process(fn ->
+        1 / 0
+      end)
+    end)
+
+    assert_eventually(
+      [
+        %{
+          id: id1,
+          datetime: datetime1,
+          level: :error,
+          kind: :error,
+          reason: %Tower.ReportEventError{
+            reporter: BuggyReporter,
+            original_exception: %RuntimeError{message: "I have a bug"}
+          },
+          stacktrace: stacktrace1
+        },
+        %{
+          id: id2,
+          datetime: datetime2,
+          level: :error,
+          kind: :error,
+          reason: %ArithmeticError{message: "bad argument in arithmetic expression"},
+          stacktrace: stacktrace2
+        }
+      ] = reported_events()
+    )
+
+    assert String.length(id1) == 36
+    assert recent_datetime?(datetime1)
+    assert is_list(stacktrace1)
+    assert String.length(id2) == 36
+    assert recent_datetime?(datetime2)
+    assert is_list(stacktrace2)
+    assert datetime1 > datetime2
+  end
+
   defp in_unlinked_process(fun) when is_function(fun, 0) do
     {:ok, pid} = Task.Supervisor.start_link()