Don't search if input is empty

index.html

@@ -83,7 +83,7 @@
             var input = removeAccents(document.getElementById('searchInput').value.toLowerCase());
 
             // 空的話就不搜尋了
-            if (input === '') {
+            if (input.trim() === '') {
                 document.getElementById('results').innerHTML = '喜歡這個工具的話，請多到 <a href="https://nicechord.com" target="_blank">NiceChord.com</a> 逛逛喔！';
                 return;
             }