Reactjs 警告：Functions are not valid as a React child, using a conditional rendering

I'm trying to display the list of results taken from the response of wikipedia API. If the response doesn't show any list, it should show a different message. I am trying to do a conditional rendering.

以下是代码:

getData(e) {
        e.preventDefault();
        var search = e.target.search.value;
        var wikipediaEndPoint = "https://en.wikipedia.org/w/api.php?format=json&origin=*&action=query&generator=search&gsrnamespace=0&prop=pageimages|extracts&pilimit=max&exintro&explaintext&exsentences=1&exlimit=max&gsrsearch="+search;
        var wikipediaUrl = "https://en.wikipedia.org/?curid=";

        fetch(wikipediaEndPoint)
        .then(data => {
            return data.json();
        }).then(data => {
            var objectList = (data.hasOwnProperty("query")) ? data.query.pages : "";
            let resultList;

            if(objectList !== ""){
                resultList = Object.keys(objectList).map(function(key, index) {
                    return (
                        <div className="item" key={objectList[key].pageid}>
                            <a href={wikipediaUrl+objectList[key].pageid}>
                                <h1>{objectList[key].title}</h1>
                                <p>{objectList[key].extract}</p>
                            </a>
                        </div>
                    )
                });
            } else {
                resultList = (function() {
                    return (
                        <div className="item" key={1}>
                            <p>No results!</p>
                        </div>
                    )
                });
            }

            this.setState({search: resultList});
        })
    }

结果如下所示:<div className="items">{this.state.search}</div>

当搜索字段关键字找到一些结果时，它可以正常工作，但是，在相反的情况下，控制台会返回错误(或警告):

Warning: Functions are not valid as a React child. This may happen if

Where is the error? Am I doing the conditional rendering the right way?

谢谢