Moved all non-net/http related code to the new Engine struct

Author: EwenQuim

engine.go

@@ -0,0 +1,16 @@
+package fuego
+
+func NewEngine() *Engine {
+	return &Engine{
+		OpenAPI:      NewOpenAPI(),
+		ErrorHandler: ErrorHandler,
+	}
+}
+
+// The Engine is the main struct of the framework.
+type Engine struct {
+	OpenAPI      *OpenAPI
+	ErrorHandler func(error) error
+
+	acceptedContentTypes []string
+}

server.go

@@ -56,25 +56,22 @@ type Server struct {
 	disableAutoGroupTags   bool
 	basePath               string // Base path of the group
 
-	// Points to the server OpenAPI struct.
-	OpenAPI *OpenAPI
+	*Engine
 
 	Security Security
 
 	autoAuth AutoAuthConfig
 	fs       fs.FS
 	template *template.Template // TODO: use preparsed templates
 
-	acceptedContentTypes []string
-
 	DisallowUnknownFields bool // If true, the server will return an error if the request body contains unknown fields. Useful for quick debugging in development.
 	DisableOpenapi        bool // If true, the routes within the server will not generate an OpenAPI spec.
 	maxBodySize           int64
 
-	Serialize      Sender                // Custom serializer that overrides the default one.
-	SerializeError ErrorSender           // Used to serialize the error response. Defaults to [SendError].
-	ErrorHandler   func(err error) error // Used to transform any error into a unified error type structure with status code. Defaults to [ErrorHandler]
-	startTime      time.Time
+	Serialize      Sender      // Custom serializer that overrides the default one.
+	SerializeError ErrorSender // Used to serialize the error response. Defaults to [SendError].
+
+	startTime time.Time
 
 	OpenAPIConfig OpenAPIConfig
 
@@ -99,8 +96,8 @@ func NewServer(options ...func(*Server)) *Server {
 			WriteTimeout:      30 * time.Second,
 			IdleTimeout:       30 * time.Second,
 		},
-		Mux:     http.NewServeMux(),
-		OpenAPI: NewOpenAPI(),
+		Mux:    http.NewServeMux(),
+		Engine: NewEngine(),
 
 		OpenAPIConfig: defaultOpenAPIConfig,
 
@@ -113,7 +110,6 @@ func NewServer(options ...func(*Server)) *Server {
 		WithDisallowUnknownFields(true),
 		WithSerializer(Send),
 		WithErrorSerializer(SendError),
-		WithErrorHandler(ErrorHandler),
 		WithRouteOptions(
 			OptionAddResponse(http.StatusBadRequest, "Bad Request _(validation or deserialization error)_", Response{Type: HTTPError{}}),
 			OptionAddResponse(http.StatusInternalServerError, "Internal Server Error _(panics)_", Response{Type: HTTPError{}}),