Amazon web services LEX:无效的Bot配置：给定当前插槽没有可用的消息

我想创建一个分支意图，在slot MeetingType==“online”的情况下，它会将用户重定向到对话底部的slot Phone，如下图所示

我的Lambda函数如下所示：

exports.handler = async (event) => {
    
    console.log(event); //capture Lex params
    
    let { name, slots } = event.currentIntent;
    
    if(!slots.InvitationLink && 
        slots.MeetingType && 
        (slots.MeetingType.toLowerCase() === 'on-line' ||
        slots.MeetingType.toLowerCase() === 'online')) {
            
            return {
                dialogAction: {
                    type: "ElicitSlot",
                    intentName: name,
                    slotToElicit: "InvitationLink",
                    slots
                }
            };
        }
        
    if(!slots.Street && 
        slots.MeetingType && 
        (slots.MeetingType.toLowerCase() === 'in-person' ||
        slots.MeetingType.toLowerCase() === 'inperson' ||
        slots.MeetingType.toLowerCase() === 'personal')) {
            
            return {
                dialogAction: {
                    type: "ElicitSlot",
                    intentName: name,
                    slotToElicit: "Street",
                    slots
                }
            };
        }
        
    if(!slots.Date &&
        slots.Street &&
        slots.MeetingType && 
        (slots.MeetingType.toLowerCase() === 'in-person' ||
        slots.MeetingType.toLowerCase() === 'inperson' ||
        slots.MeetingType.toLowerCase() === 'personal')) {
            
            return {
                dialogAction: {
                    type: "ElicitSlot",
                    intentName: name,
                    slotToElicit: "Date",
                    slots
                }
            };
        }
        
    if(!slots.Time &&
        slots.Date &&
        slots.Street &&
        slots.MeetingType && 
        (slots.MeetingType.toLowerCase() === 'in-person' ||
        slots.MeetingType.toLowerCase() === 'inperson' ||
        slots.MeetingType.toLowerCase() === 'personal')) {
            
            return {
                dialogAction: {
                    type: "ElicitSlot",
                    intentName: name,
                    slotToElicit: "Time",
                    slots
                }
            };
        }

    return {
        dialogAction: {
            type: "Delegate",
            slots
        }
    };
    
};

当我通过CONVA（插槽电话）的末尾时，会抛出以下错误：

出现错误：Bot配置无效：没有可用的消息 给定当前插槽、sessionAttribute和requestAttribute集

任何帮助都将不胜感激