For the read operation, replace the _ReadListItem function with the following code:
private _readListItem(): void { const id: number = 1; this._getListItem(id).then(listItem => { this._operationResults.innerHTML = ` <div> Read list item<br/> Title: ${listItem.Title}<br/> Info: ${listItem.Info} </div>`; }) .catch(error => { this._operationResults.innerHTML = "Read: Operation failed. "+error.message; }); } private _getListItem(id: number): Promise<ISPListItem> { const url: string = this.context.pageContext.site.absoluteUrl+ "/_api/web/lists/getbytitle('My List')/items?$select=Title,Id,Info&$filter=Id eq "+id; return this.context.spHttpClient.get(url, SPHttpClient.configurations.v1) .then((response: SPHttpClientResponse) => { return response.json(); }) .then( (listItems: any)...