Add link to screenshot if budget is failing (#3182)

lib/plugins/matrix/index.js

@@ -68,6 +68,12 @@ module.exports = {
         }
         break;
       }
+      case 'browsertime.config': {
+        if (message.data.screenshot === true) {
+          this.screenshotType = message.data.screenshotType;
+        }
+        break;
+      }
       case 'error': {
         // We can send too many messages to Matrix and get 429 so instead
         // we bulk send them all one time
@@ -96,7 +102,11 @@ module.exports = {
               if (this.resultUrls.hasBaseUrl()) {
                 text += ` (<a href="${this.resultUrls.absoluteSummaryPagePath(
                   url
-                )}index.html">result</a>)</h5>`;
+                )}index.html">result</a> - <a href="${this.resultUrls.absoluteSummaryPagePath(
+                  url
+                )}data/screenshots/1/afterPageCompleteCheck.${
+                  this.screenshotType
+                }">screenshot</a>)</h5>`;
               } else {
                 text += '</h5>';
               }