datetime date views filter: DateTime object not set

Problem/Motivation

Using datetime views filter and filtering with an invalid date, there is no validation and fatal error occured.

To reproduce:

• Add a datetime field in an entity bundle.
• Create a view to list this entities and add a filter on this datetime field
• Search for a date with wrong format or for example day in french: lun 2018-04-27. The following error occur:
  

  <em class="placeholder">Exception</em>: DateTime object not set. in <em class="placeholder">Drupal\Component\Datetime\DateTimePlus-&gt;__call()</em> (line <em class="placeholder">355</em> of <em class="placeholder">core/lib/Drupal/Component/Datetime/DateTimePlus.php</em>). <pre class="backtrace">Drupal\datetime\Plugin\views\filter\Date-&gt;opSimple(&#039;sesame_quota_option__field_sesame_opt_date.field_sesame_opt_date_value&#039;) (Line: 314)
  Drupal\views\Plugin\views\filter\NumericFilter-&gt;query() (Line: 1370)
  Drupal\views\ViewExecutable-&gt;_build(&#039;filter&#039;) (Line: 1259)
  Drupal\views\ViewExecutable-&gt;build() (Line: 390)
  Drupal\views\Plugin\views\display\PathPluginBase-&gt;execute() (Line: 180)
  Drupal\views\Plugin\views\display\Page-&gt;execute() (Line: 1627)
  Drupal\views\ViewExecutable-&gt;executeDisplay(&#039;page_1&#039;, Array) (Line: 77)
  Drupal\views\Element\View::preRenderViewElement(Array)
  call_user_func(Array, Array) (Line: 378)
  Drupal\Core\Render\Renderer-&gt;doRender(Array, ) (Line: 195)
  Drupal\Core\Render\Renderer-&gt;render(Array, ) (Line: 226)
  Drupal\Core\Render\MainContent\HtmlRenderer-&gt;Drupal\Core\Render\MainContent\{closure}() (Line: 582)
  Drupal\Core\Render\Renderer-&gt;executeInRenderContext(Object, Object) (Line: 227)
  Drupal\Core\Render\MainContent\HtmlRenderer-&gt;prepare(Array, Object, Object) (Line: 117)
  Drupal\Core\Render\MainContent\HtmlRenderer-&gt;renderResponse(Array, Object, Object) (Line: 90)
  Drupal\Core\EventSubscriber\MainContentViewSubscriber-&gt;onViewRenderArray(Object, &#039;kernel.view&#039;, Object) (Line: 76)
  Drupal\webprofiler\EventDispatcher\TraceableEventDispatcher-&gt;dispatch(&#039;kernel.view&#039;, Object) (Line: 156)
  Symfony\Component\HttpKernel\HttpKernel-&gt;handleRaw(Object, 1) (Line: 68)
  Symfony\Component\HttpKernel\HttpKernel-&gt;handle(Object, 1, 1) (Line: 57)
  Drupal\Core\StackMiddleware\Session-&gt;handle(Object, 1, 1) (Line: 47)
  Drupal\Core\StackMiddleware\KernelPreHandle-&gt;handle(Object, 1, 1) (Line: 99)
  Drupal\page_cache\StackMiddleware\PageCache-&gt;pass(Object, 1, 1) (Line: 78)
  Drupal\page_cache\StackMiddleware\PageCache-&gt;handle(Object, 1, 1) (Line: 47)
  Drupal\Core\StackMiddleware\ReverseProxyMiddleware-&gt;handle(Object, 1, 1) (Line: 38)
  Drupal\webprofiler\StackMiddleware\WebprofilerMiddleware-&gt;handle(Object, 1, 1) (Line: 50)
  Drupal\Core\StackMiddleware\NegotiationMiddleware-&gt;handle(Object, 1, 1) (Line: 23)
  Stack\StackedHttpKernel-&gt;handle(Object, 1, 1) (Line: 664)
  Drupal\Core\DrupalKernel-&gt;handle(Object) (Line: 19)

• Search for the same date with day in english works: mon 2018-04-27. Same for date only: 2018-04-27

Proposed resolution

Mimic the date filter validation from views module.

Remaining tasks

1. Add tests
2. Review