Failed to open plugin.js

Same problem here with Drupal 8.7.3. Due to this issue it crashes CKEditor rendering and CKEditor becomes useless. I would bump it up to major issue status. Unfortunately I'm not able to test the provided patch sorry (I'm a non developer user)

Warning: file_get_contents(/libraries/emojione/plugin.js): failed to open stream: No such file or directory in _locale_parse_js_file() (line 1133 of core/modules/locale/locale.module).

_locale_parse_js_file('/libraries/emojione/plugin.js') (Line: 545)
locale_js_translate(Array) (Line: 305)
Drupal\ckeditor\Plugin\Editor\CKEditor->getJSSettings(Object) (Line: 81)
Drupal\editor\Plugin\EditorManager->getAttachments(Array) (Line: 92)
Drupal\editor\Element->preRenderTextFormat(Array)
call_user_func(Array, Array) (Line: 378)
Drupal\Core\Render\Renderer->doRender(Array, ) (Line: 195)
Drupal\Core\Render\Renderer->render(Array) (Line: 501)
Drupal\Core\Template\TwigExtension->escapeFilter(Object, Array, 'html', NULL, 1) (Line: 99)
__TwigTemplate_74b8317c1d661086bcd17563cb1651da23f7201886800792d9da949c85442e47->doDisplay(Array, Array) (Line: 455)
Twig\Template->displayWithErrorHandling(Array, Array) (Line: 422)
Twig\Template->display(Array) (Line: 434)
Twig\Template->render(Array) (Line: 64)
twig_render_template('core/themes/classy/templates/form/field-multiple-value-form.html.twig', Array) (Line: 384)
Drupal\Core\Theme\ThemeManager->render('field_multiple_value_form', Array) (Line: 437)
Drupal\Core\Render\Renderer->doRender(Array) (Line: 450)
Drupal\Core\Render\Renderer->doRender(Array) (Line: 450)
Drupal\Core\Render\Renderer->doRender(Array, ) (Line: 195)
Drupal\Core\Render\Renderer->render(Array, ) (Line: 226)
Drupal\Core\Render\MainContent\HtmlRenderer->Drupal\Core\Render\MainContent\{closure}() (Line: 582)
Drupal\Core\Render\Renderer->executeInRenderContext(Object, Object) (Line: 227)
Drupal\Core\Render\MainContent\HtmlRenderer->prepare(Array, Object, Object) (Line: 117)
Drupal\Core\Render\MainContent\HtmlRenderer->renderResponse(Array, Object, Object) (Line: 90)
Drupal\Core\EventSubscriber\MainContentViewSubscriber->onViewRenderArray(Object, 'kernel.view', Object)
call_user_func(Array, Object, 'kernel.view', Object) (Line: 111)
Drupal\Component\EventDispatcher\ContainerAwareEventDispatcher->dispatch('kernel.view', Object) (Line: 156)
Symfony\Component\HttpKernel\HttpKernel->handleRaw(Object, 1) (Line: 68)
Symfony\Component\HttpKernel\HttpKernel->handle(Object, 1, 1) (Line: 57)
Drupal\Core\StackMiddleware\Session->handle(Object, 1, 1) (Line: 47)
Drupal\Core\StackMiddleware\KernelPreHandle->handle(Object, 1, 1) (Line: 106)
Drupal\page_cache\StackMiddleware\PageCache->pass(Object, 1, 1) (Line: 85)
Drupal\page_cache\StackMiddleware\PageCache->handle(Object, 1, 1) (Line: 47)
Drupal\Core\StackMiddleware\ReverseProxyMiddleware->handle(Object, 1, 1) (Line: 52)
Drupal\Core\StackMiddleware\NegotiationMiddleware->handle(Object, 1, 1) (Line: 23)
Stack\StackedHttpKernel->handle(Object, 1, 1) (Line: 693)
Drupal\Core\DrupalKernel->handle(Object) (Line: 19)

Patch from #2 comment solves the issue.

Thank you, Manuel Adán (manuel.adan) !

Committed and pushed to 8.x-1.x, closing issue. Thanks for everyone's help!

Merged and tagged into 8.x-1.1 branch.