✨ Refactor ResponseHelper and add ResponderHandler

- Modified ResponseHelper.Body signature to return an io.Reader and an error.
- Updated ResponseHandler.ServeHTTP to handle errors from ResponseHelper.Body.
- Implemented JSONResponse and JSONResponseWithStatus functions for easier JSON responses.
- Added comprehensive unit tests for JSON response handling, including error scenarios.
- Extended Helper.ResponderHandler with a new test case to ensure proper error handling and response generation.
- Resolved linting issues related to dynamic error definition and function length in tests.

response.go

@@ -0,0 +1,56 @@
+package ezhandler
+
+import (
+	"bytes"
+	"encoding/json"
+	"io"
+	"net/http"
+)
+
+// ResponseHelper is a simpler way to return a response.
+type ResponseHelper interface {
+	// Body returns the body of the response. It is written to an [http.ResponseWriter].
+	Body() (io.Reader, error)
+	// Status should be a valid HTTP status.
+	Status() int
+	// Headers returns headers that should be added to the response.
+	Headers() http.Header
+}
+
+type jsonResponse struct {
+	value  any
+	status int
+}
+
+var _ ResponseHelper = new(jsonResponse)
+
+func (j *jsonResponse) Body() (io.Reader, error) {
+	b, err := json.Marshal(j.value)
+	if err != nil {
+		return nil, err
+	}
+	return bytes.NewReader(b), nil
+}
+
+func (j *jsonResponse) Status() int {
+	return j.status
+}
+
+func (j *jsonResponse) Headers() http.Header {
+	header := make(http.Header)
+	header.Set("Content-Type", "application/json")
+	return header
+}
+
+// JSONResponse returns a [ResponseHelper] that JSON encodes value with a 200 response.
+func JSONResponse(value any) ResponseHelper {
+	return JSONResponseWithStatus(value, http.StatusOK)
+}
+
+// JSONResponseWithStatus returns a [ResponseHelper] that JSON encodes value with the provided status.
+func JSONResponseWithStatus(value any, status int) ResponseHelper {
+	return &jsonResponse{
+		value:  value,
+		status: status,
+	}
+}