Laravel Error handling

Introduction
When you start a new Laravel project, error and exception handling is already configured for you. The App\Exceptions\Handler class is where all exceptions triggered by your application are logged and then rendered back to the user. We’ll dive deeper into this class throughout this documentation.
既に実装されているらしい。

Configuration
The debug option in your config/app.php configuration file determines how much information about an error is actually displayed to the user. By default, this option is set to respect the value of the APP_DEBUG environment variable, which is stored in your .env file.

For local development, you should set the APP_DEBUG environment variable to true. In your production environment, this value should always be false. If the value is set to true in production, you risk exposing sensitive configuration values to your application’s end users.

The Report Method
All exceptions are handled by the App\Exceptions\Handler class. This class contains two methods: report and render. We’ll examine each of these methods in detail. The report method is used to log exceptions or send them to an external service like Bugsnag or Sentry. By default, the report method passes the exception to the base class where the exception is logged. However, you are free to log exceptions however you wish.

For example, if you need to report different types of exceptions in different ways, you may use the PHP instanceof comparison operator:

public function report(Exception $exception)
{
    if ($exception instanceof CustomException) {
        //
    }

    return parent::report($exception);
}

The report Helper
Sometimes you may need to report an exception but continue handling the current request. The report helper function allows you to quickly report an exception using your exception handler’s report method without rendering an error page:

public function isValid($value)
{
    try {
        // Validate the value...
    } catch (Exception $e) {
        report($e);

        return false;
    }
}

Ignoring Exceptions By Type
The $dontReport property of the exception handler contains an array of exception types that will not be logged. For example, exceptions resulting from 404 errors, as well as several other types of errors, are not written to your log files. You may add other exception types to this array as needed:

protected $dontReport = [
    \Illuminate\Auth\AuthenticationException::class,
    \Illuminate\Auth\Access\AuthorizationException::class,
    \Symfony\Component\HttpKernel\Exception\HttpException::class,
    \Illuminate\Database\Eloquent\ModelNotFoundException::class,
    \Illuminate\Validation\ValidationException::class,
];

Reportable & Renderable Exceptions

namespace App\Exceptions;

use Exception;

class RenderException extends Exception
{
    /**
     * Report the exception.
     *
     * @return void
     */
    public function report()
    {
        //
    }

    /**
     * Render the exception into an HTTP response.
     *
     * @param  \Illuminate\Http\Request
     * @return \Illuminate\Http\Response
     */
    public function render($request)
    {
        return response(...);
    }
}

Some exceptions describe HTTP error codes from the server. For example, this may be a “page not found” error (404), an “unauthorized error” (401) or even a developer generated 500 error. In order to generate such a response from anywhere in your application, you may use the abort helper:

abort(404);
The abort helper will immediately raise an exception which will be rendered by the exception handler. Optionally, you may provide the response text:

abort(403, ‘Unauthorized action.’);
Custom HTTP Error Pages
Laravel makes it easy to display custom error pages for various HTTP status codes. For example, if you wish to customize the error page for 404 HTTP status codes, create a resources/views/errors/404.blade.php. This file will be served on all 404 errors generated by your application. The views within this directory should be named to match the HTTP status code they correspond to. The HttpException instance raised by the abort function will be passed to the view as an $exception variable:

{{ $exception->getMessage() }}

abort, カスタマイズなど対応している。