"attribute <items> is of the wrong type: " in lightning component

Question

i am trying to use a wrapper class list in aura:attribute i am getting the error org.auraframework.throwable.AuraRuntimeException: attribute is of the wrong type:

i'm not sure why this is happening

Component

<aura:component controller="DispositionController" implements="force:appHostable,flexipage:availableForAllPageTypes,forceCommunity:availableForAllPageTypes">   

<aura:attribute name="inventoryList" type="lotWrapper[]" default="[]" description="This attr. will hold all product Info"/>


</aura:component >

Apex class

public class lotWrapper {

@AuraEnabled public list<string> reasonToChange{get;set;}

@AuraEnabled public string newStatusVal{get;set;}

@AuraEnabled public string allocateAttrVal{get;set;}


@AuraEnabled public List<productListwrap> productListwrap{get;set;}

public lotWrapper(){

}
    public class productListwrap
    {

    @AuraEnabled public Inventory_Detail__c invDetail{get;set;}

    }
}

any help appreciated this is really urgent to me