YangExplorer.html crashes in Mozilla Firefox 61.0.1

[sadovski]

Installed yang-explorer, started server with sudo ./start.sh, got the following:

akivas@akivas-VirtualBox:~/yang-explorer$ sudo ./start.sh
[sudo] password for akivas: 

Starting YangExplorer server ..
Use http://localhost:8088/static/YangExplorer.html

Performing system checks...

System check identified no issues (0 silenced).
August 09, 2018 - 13:55:19
Django version 1.8.3, using settings 'server.settings'
Starting development server at http://localhost:8088/
Quit the server with CONTROL-C.

However when I try to access the server from Firefox YangExplorer.html crashes. In browser console I'm getting the following messages:

The page was reloaded, because the character encoding declaration of the HTML document was not found when prescanning the first 1024 bytes of the file. The encoding declaration needs to be moved to be within the first 1024 bytes of the file. YangExplorer.html:32
[Show/hide message details.] [Exception... "Component returned failure code: 0x80520006 (NS_ERROR_FILE_TARGET_DOES_NOT_EXIST) [nsIProcess.init]"  nsresult: "0x80520006 (NS_ERROR_FILE_TARGET_DOES_NOT_EXIST)"  location: "JS frame :: jar:file:///usr/lib/firefox/omni.ja!/components/CrashService.js :: runMinidumpAnalyzer/< :: line 51"  data: no]
NS_ERROR_NOT_IMPLEMENTED: PluginContent.jsm:1073
[Show/hide message details.] [Exception... "Component returned failure code: 0x80520006 (NS_ERROR_FILE_TARGET_DOES_NOT_EXIST) [nsIProcess.init]"  nsresult: "0x80520006 (NS_ERROR_FILE_TARGET_DOES_NOT_EXIST)"  location: "JS frame :: jar:file:///usr/lib/firefox/omni.ja!/components/CrashService.js :: runMinidumpAnalyzer/< :: line 51"  data: no]
NS_ERROR_NOT_IMPLEMENTED: PluginContent.jsm:1073
[Show/hide message details.] [Exception... "Component returned failure code: 0x80520006 (NS_ERROR_FILE_TARGET_DOES_NOT_EXIST) [nsIProcess.init]"  nsresult: "0x80520006 (NS_ERROR_FILE_TARGET_DOES_NOT_EXIST)"  location: "JS frame :: jar:file:///usr/lib/firefox/omni.ja!/components/CrashService.js :: runMinidumpAnalyzer/< :: line 51"  data: no]
NS_ERROR_NOT_IMPLEMENTED: PluginContent.jsm:1073
[Show/hide message details.] [Exception... "Component returned failure code: 0x80520006 (NS_ERROR_FILE_TARGET_DOES_NOT_EXIST) [nsIProcess.init]"  nsresult: "0x80520006 (NS_ERROR_FILE_TARGET_DOES_NOT_EXIST)"  location: "JS frame :: jar:file:///usr/lib/firefox/omni.ja!/components/CrashService.js :: runMinidumpAnalyzer/< :: line 51"  data: no]
JQMIGRATE: Logging is active

Any idea what what's wrong with my installation?

Thank you, Akiva