Strict warning and Undefined index

PHP 5.4.39

I've done some testing and would say: No the problem is only partly fixed. The warings are not at the "turnjs_magazines" sites any more, but on some of the pages showing a normal content node

Notice: Undefined property: stdClass::$type in turnjs_magazines_entity_view() (line 57 of /homepages/44/d513036722/htdocs/sites/all/modules/turnjs_magazines/turnjs_magazines.module).

It is strange, the pages do not have any link to turnjs_magazines ....

We do still have tons of this warnings:

Notice: Undefined property: stdClass::$type in turnjs_magazines_entity_view() (line 57 of /homepages/44/d513036722/htdocs/sites/all/modules/turnjs_magazines/turnjs_magazines.module).

Would you help us to get rid of it?

We sill have the problem and are still not experienced in PHP. So please, could someone give us a hint how to get rid of this warning. In the mean time we have many PDFs and tons of warinings in the logfile:

The message is:
Notice: Undefined property: stdClass::$type in turnjs_magazines_entity_view() (line 57 of /homepages/44/d513036722/htdocs/sites/all/modules/turnjs_magazines/turnjs_magazines.module).

and the code is:

52 /**
53  * Implements hook_entity_view().
54  */
55 function turnjs_magazines_entity_view($entity, $type, $view_mode, $langcode) {
56   // The teaser display can be used to link to magazines. We remove unwanted elements here.
57  if ($entity->type == TURNJS_MAGAZINES_NODE_TYPE && $view_mode == 'teaser') {
58     // Only show the first image of the field in teaser display (for references). This is currently not possible in field settings.
59     $entity->content[TURNJS_MAGAZINES_FIELD_RESULTING_IMAGES]['#items'] = array_slice($entity->content[TURNJS_MAGAZINES_FIELD_RESULTING_IMAGES]['#items'], 0, 1);
60     if (isset($entity->content['links'])) {
61       // Hide the further links for the teaser.
62       // hide() does not work here. Got no clue, why.
63       unset($entity->content['links']);
64     }
65     // Hide the title.
66     $entity->title = NULL;
67   }
68 }

Is there something we should add in the IF statement?

Yep, the missing "isset" was the problem.
Thank you!