Check if $primaryKey is present before execute the unset

Author: FormigTeen

src/Relations/EmbedsMany.php

@@ -152,7 +152,7 @@ public function dissociate($ids = [])
 
         // Remove the document from the parent model.
         foreach ($records as $i => $record) {
-            if (in_array($record[$primaryKey], $ids)) {
+            if (array_key_exists($primaryKey, $record) && in_array($record[$primaryKey], $ids)) {
                 unset($records[$i]);
             }
         }