WSOD when accessing non-enabled or non-existent source plugin

Problem/Motivation

I first encountered this when using the Drupal CMS trial on Acquia.

It did not occur locally when clicking browse Modules.

@timplunkett mentioned the trial has:
$config['project_browser.admin_settings']['enabled_sources'] = ['recipes'];
in settings.php

Adding this locally reproduces it.

Steps to reproduce

Add $config['project_browser.admin_settings']['enabled_sources'] = ['recipes']; to settings.php
Visit /admin/modules/browse/drupalorg_jsonapi

The website encountered an unexpected error. Try again later.

AssertionError: assert($source instanceof ProjectBrowserSourceInterface) in assert() (line 117 of modules/contrib/project_browser/src/Element/ProjectBrowser.php).

Drupal\project_browser\Element\ProjectBrowser->getDrupalSettings() (Line: 96)
Drupal\project_browser\Element\ProjectBrowser->attachProjectBrowserSettings()
call_user_func_array() (Line: 107)
Drupal\Core\Render\Renderer->doTrustedCallback() (Line: 825)
Drupal\Core\Render\Renderer->doCallback() (Line: 387)
Drupal\Core\Render\Renderer->doRender() (Line: 203)
Drupal\Core\Render\Renderer->render() (Line: 238)
Drupal\Core\Render\MainContent\HtmlRenderer->Drupal\Core\Render\MainContent\{closure}() (Line: 593)
Drupal\Core\Render\Renderer->executeInRenderContext() (Line: 231)
Drupal\Core\Render\MainContent\HtmlRenderer->prepare() (Line: 128)
Drupal\Core\Render\MainContent\HtmlRenderer->renderResponse() (Line: 90)
Drupal\Core\EventSubscriber\MainContentViewSubscriber->onViewRenderArray() (Line: 246)
Symfony\Component\EventDispatcher\EventDispatcher::Symfony\Component\EventDispatcher\{closure}() (Line: 206)
Symfony\Component\EventDispatcher\EventDispatcher->callListeners() (Line: 56)
Symfony\Component\EventDispatcher\EventDispatcher->dispatch() (Line: 188)
Symfony\Component\HttpKernel\HttpKernel->handleRaw() (Line: 76)
Symfony\Component\HttpKernel\HttpKernel->handle() (Line: 53)
Drupal\Core\StackMiddleware\Session->handle() (Line: 48)
Drupal\Core\StackMiddleware\KernelPreHandle->handle() (Line: 28)
Drupal\Core\StackMiddleware\ContentLength->handle() (Line: 32)
Drupal\big_pipe\StackMiddleware\ContentLength->handle() (Line: 116)
Drupal\page_cache\StackMiddleware\PageCache->pass() (Line: 90)
Drupal\page_cache\StackMiddleware\PageCache->handle() (Line: 48)
Drupal\Core\StackMiddleware\ReverseProxyMiddleware->handle() (Line: 51)
Drupal\Core\StackMiddleware\NegotiationMiddleware->handle() (Line: 36)
Drupal\Core\StackMiddleware\AjaxPageState->handle() (Line: 51)
Drupal\Core\StackMiddleware\StackedHttpKernel->handle() (Line: 709)
Drupal\Core\DrupalKernel->handle() (Line: 19)

Proposed resolution

This issue will turn the WSOD into a 404, removing the incorrect link will happen in #3500078: Drupal CMS default content links to Project Browser source disabled in the Trial