Question TypeError: document.postform.subject.focus when adding image/link

Hi,
here is the situation:
* joomla 3.6.5
* Template Shaper Helix 3
* kunena 5.0.6.1

the forum is published and i can start a new topic.

The issue happens when i want to add link or image in the topic.
When i click on the link/image button, the screen comes grey and then nothing.
When i examine element, i found the error "TypeError: document.postform.subject.focus is not a function"

what kind of informations do you need to analyze the issue ?

when inspecting element i found :

<div class="modal-backdrop fade in"></div>

[HTTP/1.1 404 Not Found 1 ms] GET {my local site}/templates/shaper_helix3/css/bootstrap.min.css.map

the file does not exist
I tried ti add this file, but the issue persists

in fact, all modal windows don't work

I just installed a fresh joomla 3.6.5 with protostar template, then kunena 5.0.6.1 and it works fine.
Is there incompatibilities between kunena and Shaper Helix 3 template ?

Is there incompatibilities between kunena and Shaper Helix 3 template ?[/b]

I don't think so.. It seems the template installation was not complete correct. Install it again. If it still not works, you can also try it with the Kunena nightly build from our download page.

I think you're right because i got errors during installation. But after going in kunena menu, the installation was finished, so i believed that all was ok.

I will try again the installation. Thks

I confirm that kunena doesn't work with shaper helix 3 template.
i took my fresh install joomla 3.6.5 with kunena 5.0.6.1, all works with protostar template.
I've installed shaper helix 3 v1.9, i've activated helix template and i've got same errors.

so there's incompatibilities between kunena and helix 3 template

I am also getting the error: Uncaught TypeError: document.postform.subject.focus is not a function
without trying to load anything.
Just by going to the new topic page
I don't see the error in my testing environment, only in my production site.

Tested with:
Joomla version: 3.8.7
Kunena version: 5.1.0
Php version: 7.2.5
Database version: MySQL 5.6.39

OS: [Windows]
Browser [Google Chrome]
Version [Version 66.0.3359.170]