Fixed Bug (#3596)

Fixed bug, when need create bread and DataType table does not has row with this "table name"
trying to get property 'model_name'

Author: jovixv

src/Http/Controllers/VoyagerBreadController.php

@@ -54,7 +54,7 @@ public function create(Request $request, $table)
         $dataType = Voyager::model('DataType')->whereName($table)->first();
 
         $data = $this->prepopulateBreadInfo($table);
-        $data['fieldOptions'] = SchemaManager::describeTable((strlen($dataType->model_name) != 0)
+        $data['fieldOptions'] = SchemaManager::describeTable((isset($dataType) && strlen($dataType->model_name) != 0)
             ? app($dataType->model_name)->getTable()
             : $table
         );