In developer console and log are no related messages.
Suggestion
Could the dialog be extended by the affected file and link? This would make debugging much easier.
Or even one step further: Do we need a dialog jumping at the user, since the file is imported anyway? Wouldn't it be sufficient to just add a log message?
I think the URI Error is not quite useful and we can ignore it. It is generated when decoding the URIs in the markdown file with decodeURI() and trying to parsing the resource link. If a link cannot be decoded, it should be kept as the original one.