fix(github): skip when no body sent

Author: stilliard

src/check-outstanding-tasks.js

@@ -1,6 +1,9 @@
 const marked = require('marked');
 
 module.exports = function (body) {
+    if (body === null) {
+        return false;
+    }
     let tokens = marked.lexer(body, { gfm: true });
     let listItems = tokens.filter(token => token.type === 'list_item_start');