PLT-5722 Fix formatText to fail gracefully when input is not text (#5670)

* Updated marked to remove incorrect error message

* Fix formatText to fail gracefully when input is not text

webapp/package.json

@@ -17,7 +17,7 @@
     "intl": "1.2.5",
     "jasny-bootstrap": "3.1.3",
     "jquery": "3.1.1",
-    "marked": "mattermost/marked#328857681dcc98a3d75633d6c0effa7c29b6cceb",
+    "marked": "mattermost/marked#8f5902fff9bad793cd6c66e0c44002c9e79e1317",
     "match-at": "0.1.0",
     "object-assign": "4.1.1",
     "pdfjs-dist": "1.7.235",