出现错误 Undocumented TypeError: Failed to fetch

原因: 跨域导致

处理问题

app\Middleware\CoreMiddleware.php

<?php
declare(strict_types=1);

namespace App\Middleware;

use Hyperf\Utils\Context;
use Psr\Http\Message\ResponseInterface;
use Psr\Http\Message\ServerRequestInterface;
use Psr\Http\Server\MiddlewareInterface;
use Psr\Http\Server\RequestHandlerInterface;

class CoreMiddleware implements MiddlewareInterface
{
    public function process(ServerRequestInterface $request, RequestHandlerInterface $handler): ResponseInterface
    {
        // TODO: Implement process() method.
        $response = Context::get(ResponseInterface::class);
        $response = $response->withHeader('Access-Control-Allow-Origin', '*')
            ->withHeader('Access-Control-Allow-Credentials', 'true')
            // Headers 可以根据实际情况进行改写。
            ->withHeader('Access-Control-Allow-Headers', 'DNT,Keep-Alive,User-Agent,Cache-Control,Content-Type,Authorization');

        Context::set(ResponseInterface::class, $response);

        if ($request->getMethod() == 'OPTIONS') {
            return $response;
        }

        return $handler->handle($request);
    }
}

\config\autoload\middlewares.php

return [
    'http' => [
        \Hyperf\Session\Middleware\SessionMiddleware::class,
        \App\Middleware\CoreMiddleware::class #增加这一行代码
    ],
];