Misleading error reported due to control flow in config check

[teskanoo]

Checklist:

• [*] I updated to the latest version available
• [*] I cleared the cache of my browser

Release with the issue:
Version 0.6.3
Last working release (if known):

Browser and Operating System:

Windows Chrome

Description of problem:

I'm seeing this in the front-end but it took me a while to track it down as the error is a bit misleading.

The cause of the issue is in fact that I forgot to add the object decluttering_templates to my main lovelace config

The error occurs when the code is checking that decluttering exists in the config (js object)

These line numbers are not going to help but I'm sure you can find the code

The exception on line 1717 never gets thrown because of the way the the pre-check is being done

I think you need...
if (!t.config || ('decluttering_templates' in !t.config))

When I run this in the console it behaves as expected

Javascript errors shown in the web inspector (if applicable):

Additional information: