Add error page when accept header is text/html

handlers/error_page.go

@@ -0,0 +1,33 @@
+package handlers
+
+import (
+	"bytes"
+	"embed"
+	"fmt"
+	"html/template"
+	"strings"
+
+	"github.com/gofiber/fiber/v2"
+)
+
+//go:embed error_page.html
+var errorHTML embed.FS
+
+func RenderErrorPage() fiber.Handler {
+	f := "error_page.html"
+	tmpl, err := template.ParseFS(errorHTML, f)
+	if err != nil {
+		panic(fmt.Errorf("RenderErrorPage Error: %s not found", f))
+	}
+	return func(c *fiber.Ctx) error {
+		if err := c.Next(); err != nil {
+			if strings.Contains(c.Get("Accept"), "text/html") {
+				c.Set("Content-Type", "text/html")
+				tmpl.Execute(c.Response().BodyWriter(), err.Error())
+				return nil
+			}
+			return c.SendStream(bytes.NewBufferString(err.Error()))
+		}
+		return err
+	}
+}