docs: error handling

documentation/docs/guides/errors.mdx

@@ -6,3 +6,33 @@ Error handling is a crucial part of any application. It is important to handle e
 
 
 <FlowChart selected="ErrorHandler" />
+
+## Error handling in Fuego
+
+Fuego [controllers](./controllers) returns a value and an error. If the error is not `nil`, it means that an error occurred while processing the request. The error will be returned to the client as a JSON response.
+
+The error type returned as JSON is `fuego.HTTPError`. It has a `Status` and a `Info` field. The `Status` field is an integer that represents the error code. The `Info` field is a string that contains a human-readable error message.
+
+If your error implements `Status() int` and `Info()` methods, the error will include the status code and the error message in the `fuego.HTTPError` response.
+
+```go
+type MyCustomError struct {
+	Status int
+	Message string
+}
+
+func (e MyCustomError) Status() int {
+	return e.Status
+}
+```
+
+## Default errors
+
+Fuego provides a set of default errors that you can use in your application.
+
+- `fuego.BadRequestError`: 400 Bad Request
+- `fuego.UnauthorizedError`: 401 Unauthorized
+- `fuego.ForbiddenError`: 403 Forbidden
+- `fuego.NotFoundError`: 404 Not Found
+- `fuego.ConflictError`: 409 Conflict
+- `fuego.InternalServerError`: 500 Internal Server Error