Update static/app.js

static/app.js

@@ -18,6 +18,8 @@ function updateInfo() {
 }
 
 function search() {
+    let pos = board.position();
+    if (Object.keys(pos).length < 3) { document.getElementById('results').innerHTML = '<p>Add at least 3 pieces to search.</p>'; return; }
     document.getElementById('results').innerHTML = '<p>Searching...</p>';
     fetch('/search', {
         method: 'POST',