[Bug] When you first install a theme, you cannot configure it (need to activate first)

[Jonius7]

Before Reporting

• I found no existing issues matching my bug
• My issue is not caused by a theme
• My issue is not caused by a plugin

Describe the Bug

A minor issue, but one I got stuck over for some minutes.

When you first install a theme, and you try to configure it under Themes -> ... -> Configure , you will get an error like this.

Expected Behavior

To be able to configure the settings for a theme immediately after install.

Steps To Reproduce

1. Make sure the theme you are installing doesn't already exist in steamui/skins
2. Install a theme (copying Theme ID and adding it in Millennium)
3. After Steam window reloads, click Themes -> under the theme you just installed click ... -> Configure
4. Receive the error and unable to configure theme.

Operating System

Windows

Anything else?

The workaround is to activate the theme and then the configuration settings will be available.

[shdwmtr]

Is this only with certain themes?

[Jonius7]

So it happened initially (and consistently) when I was trying to set up my own theme (currently in development) but it also happened when I added Zehn theme to the system.

Though I am testing today and I cannot seem to replicate it, it may be because my theme was lacking material at the time.

[Jonius7]

A bit more information, I think it has to do with invalid/incomplete skin.json even if it's valid JSON.
And I am able to replicate it now by renaming an existing theme folder in steamui to a new name.

[shdwmtr]

So to clarify, the skin.json is completely valid and in full on disk, but Millennium isn't recognizing that?

[Jonius7]

I believe so, the error appears for any theme that can be configured. (Just renamed the simple-dark folder so Millennium treats it like a new theme)