feat(problems): add more context to the default text response

Author: ConsoleTVs

problem.go

@@ -262,8 +262,28 @@ func ProblemControlsResponseFrom(responses map[string]Builder) ProblemControlsRe
 			}
 		}
 
+		textResponse := fmt.Sprintf(
+			"%d %s\n\n%s",
+			problem.Status,
+			problem.Title,
+			problem.Detail,
+		)
+
+		controls := problem.controls(request)
+
+		errors, found := problem.Additional(controls.ErrorsKey(problem, request))
+		traces, tracesOK := errors.([]string)
+
+		if found && tracesOK && controls.Errors(problem, request) {
+			textResponse += fmt.Sprintf("\n\n")
+
+			for _, trace := range traces {
+				textResponse += fmt.Sprintf("%s\n", trace)
+			}
+		}
+
 		return Response(problem.Status).
-			Text(fmt.Sprintf("%d %s\n\n%s", problem.Status, problem.Title, problem.Detail))
+			Text(textResponse)
 	}
 }
 

problem_test.go

@@ -5,6 +5,7 @@ import (
 	"errors"
 	"fmt"
 	"net/http"
+	"strings"
 	"testing"
 
 	"github.com/studiolambda/akumu"
@@ -163,6 +164,21 @@ func TestProblemWithCustomError(t *testing.T) {
 	}
 }
 
+func TestProblemWithCustomError2(t *testing.T) {
+	request, err := http.NewRequest("GET", "/", nil)
+
+	if err != nil {
+		t.Fatalf("unable to create request: %s", err)
+	}
+
+	response := akumu.Record(customProblemHandlerWithErr, request)
+	res := string(response.Body.Bytes())
+
+	if expect := "last error: failed"; !strings.Contains(res, expect) {
+		t.Fatalf("error should contain '%s'", expect)
+	}
+}
+
 func TestProblemDirectError(t *testing.T) {
 	request, err := http.NewRequest("GET", "/", nil)