Adds Error message for when there are no screenshots and the developer might need to wait for a promise

Author: diyaayay

test/unit/visual/visualTest.js

@@ -151,6 +151,12 @@ window.visualTest = function(
         actual.push(myp5.get());
       });
 
+
+      if (actual.length === 0) {
+        throw new Error('No screenshots were generated. Check if your test generates screenshots correctly.If the test includes asynchronous operations, ensure they complete before the test ends.');
+      }
+
+
       if (expectedScreenshots && actual.length !== expectedScreenshots) {
         throw new Error(
           `Expected ${expectedScreenshots} screenshot(s) but generated ${actual.length}`