It is causing error after Upload the document.

[goldservice2017]

I installed all packages and dependencies after cloning the repository.
Node Version: v10.4.1
NPM Version: 6.1.0

Also I added my IBM Cloud credentials(user email and password) in .env configuration file( CNC_USERNAME, CNC_PASSWORD).

I am running this node sever successfully without any error.
After I upload any PDF document( I just used sample PDF document in sample-PDFs), I got the errors in consoles as following:
htmltagging.js:31 Uncaught TypeError: Cannot read property 'substring' of undefined
at _generateLabeledHtmlText (htmltagging.js:31)
at tagHtmlDocument (htmltagging.js:7)
at handleParseResponse (main.js:60)
at Dropzone.success ((index):89)
at Dropzone.emit (dropzone.js:84)
at Dropzone._finished (dropzone.js:2796)
at Dropzone._finishedUploading (dropzone.js:2731)
at XMLHttpRequest.xhr.onload (dropzone.js:2421)

I also attached the screenshots:

Please give me help to fix them.
Thank you.