On null input "implode(): Invalid arguments passed" in laravel

I am using laravel 5.5 I have a multi-select dropdown. if I don't select any value it generates an error. "implode(): Invalid arguments passed"

<select  multiple="multiple" name="language[]">
@foreach($language_data as $language)
   <option value=""></option>
@endforeach
</select>

Controller

  $language = $request->input('language');
  $language = implode(',', $language);
 DB::table('language')->insert(['language' => $language,]);

via Chebli Mohamed