fix optional callback

node_app/mastodonMemeBot.js

@@ -11,22 +11,22 @@ export class mastodonMemeBot {
             access_token: config.accessToken,
         });
     }
-    postRandomMeme(callback = undefined) {
+    postRandomMeme(callback = () => {}) {
         this.memeHandler.getRandomMeme(sub => {
             let status = `"${sub.title}"\n${sub.text}\nby ${sub.author}`;
             if (!this.allowedMedia.find(type => type === sub.url.split(/[.]+/).pop())) {
                 console.log("no valid media, fetching new sub");
-                this.postRandomMeme(callback??undefined);
+                this.postRandomMeme(callback);
                 return;
             }
             let filepath = `./media/${sub.url.split(/[/]+/).pop()}`;
             if (getStat(filepath) === true) {
                 console.log("post already exists, fetching new sub");
-                this.postRandomMeme(callback??undefined);
+                this.postRandomMeme(callback);
                 return;
             }
             this.memeHandler.downloadMedia(sub.url, filepath, () => {
-                this.client.postMedia(status, filepath, 5, () => this.postRandomMeme(), callback??undefined);
+                this.client.postMedia(status, filepath, 5, () => this.postRandomMeme(), callback);
             })
         })
     }