Actually fix empty frames in stacktraces

See #787.

lib/sentry/client.ex

@@ -287,24 +287,27 @@ defmodule Sentry.Client do
   defp render_exception(%Interfaces.Exception{} = exception) do
     exception
     |> Map.from_struct()
-    |> render_stacktrace()
+    |> render_or_delete_stacktrace()
     |> update_if_present(:mechanism, &Map.from_struct/1)
   end
 
   defp render_thread(%Interfaces.Thread{} = thread) do
     thread
     |> Map.from_struct()
-    |> render_stacktrace()
+    |> render_or_delete_stacktrace()
   end
 
-  defp render_stacktrace(map) do
-    case map do
-      %{stacktrace: %{frames: %Interfaces.Stacktrace{frames: [_ | _]} = stacktrace}} ->
-        %{stacktrace | frames: Enum.map(stacktrace.frames, &Map.from_struct/1)}
+  # If there are frames, render the stacktrace, otherwise delete it altogether from the map.
+  defp render_or_delete_stacktrace(
+         %{stacktrace: %Interfaces.Stacktrace{frames: [_ | _]}} = exception_or_thread
+       ) do
+    exception_or_thread
+    |> Map.update!(:stacktrace, &Map.from_struct/1)
+    |> update_in([:stacktrace, :frames, Access.all()], &Map.from_struct/1)
+  end
 
-      map_without_stacktrace ->
-        Map.delete(map_without_stacktrace, :stacktrace)
-    end
+  defp render_or_delete_stacktrace(exception_or_thread) do
+    Map.delete(exception_or_thread, :stacktrace)
   end
 
   defp remove_nils(map) when is_map(map) do
@@ -362,11 +365,8 @@ defmodule Sentry.Client do
 
   defp update_if_present(map, key, fun) do
     case Map.pop(map, key) do
-      {nil, _} ->
-        map
-
-      {value, map} ->
-        Map.put(map, key, fun.(value))
+      {nil, _} -> map
+      {value, map} -> Map.put(map, key, fun.(value))
     end
   end
 

test/sentry/client_test.exs

@@ -84,22 +84,63 @@ defmodule Sentry.ClientTest do
       :code.purge(RaisingJSONClient)
     end
 
-    test "renders threads with stacktrace property deleted if :frames field set to nil if empty" do
+    test "renders stacktrace for threads" do
+      event =
+        Event.create_event(
+          message: "Stacktrace for threads",
+          stacktrace: [
+            {Kernel, :apply, 3, [file: "lib/kernel.ex", line: 1]},
+            {URI, :new!, 1, [file: "lib/uri.ex", line: 2]}
+          ]
+        )
+
+      assert %{threads: [thread]} = Client.render_event(event)
+
+      refute is_struct(thread.stacktrace),
+             ":stacktrace shouldn't be a struct, got: #{inspect(thread.stacktrace)}"
+
+      assert [
+               %{module: URI, function: "URI.new!/1", filename: "lib/uri.ex", lineno: 2},
+               %{module: Kernel, function: "Kernel.apply/3", filename: "lib/kernel.ex", lineno: 1}
+             ] = thread.stacktrace.frames
+    end
+
+    test "renders threads with :stacktrace property deleted if :frames field set to nil if empty" do
       event =
         Event.create_event(message: "No frames in stacktrace", stacktrace: [])
 
-      client = Client.render_event(event)
+      assert %{threads: [thread]} = Client.render_event(event)
+      refute Map.has_key?(thread, :stacktrace)
+    end
+
+    test "renders stacktrace for exceptions" do
+      event =
+        Event.transform_exception(
+          %RuntimeError{message: "foo"},
+          stacktrace: [
+            {Kernel, :apply, 3, [file: "lib/kernel.ex", line: 1]},
+            {URI, :new!, 1, [file: "lib/uri.ex", line: 2]}
+          ]
+        )
+
+      assert %{exception: [exception]} = Client.render_event(event)
+
+      refute is_struct(exception.stacktrace),
+             ":stacktrace shouldn't be a struct, got: #{inspect(exception.stacktrace)}"
 
-      assert is_nil(get_in(client.threads, [Access.at(0), :stacktrace]))
+      assert [
+               %{module: URI, function: "URI.new!/1", filename: "lib/uri.ex", lineno: 2},
+               %{module: Kernel, function: "Kernel.apply/3", filename: "lib/kernel.ex", lineno: 1}
+             ] = exception.stacktrace.frames
     end
 
-    test "renders exception with stacktrace property deleted if :frames field set to nil if empty" do
+    test "renders exception with :stacktrace property deleted if :frames field set to nil if empty" do
       event =
         Event.transform_exception(%RuntimeError{message: "foo"}, stacktrace: [])
 
-      client = Client.render_event(event)
+      assert %{exception: [exception]} = Client.render_event(event)
 
-      assert is_nil(get_in(client.exception, [Access.at(0), :stacktrace]))
+      refute Map.has_key?(exception, :stacktrace)
     end
 
     test "removes non-payload fields" do