Fix divide by zero

If no tests are found it would be nicer to display 0% than NaN%.

lib/panel.js

@@ -47,7 +47,7 @@ class Panel {
 
 		const summary = this.htmlRendererHelper.createContainer('summary');
 		const passed = results.pass - (results.skip ? results.skip : 0);
-		const percentage = Math.round((passed / results.count) * 100);
+		const percentage = results.count ? Math.round((passed / results.count) * 100) : 0;
 		summary.textContent = `${results.count} total - ${percentage}% passed`;
 
 		this.testsContainer.appendChild(summary);