Your theme appears to be in the wrong directory for the theme name

Hi!

I get the error:

WARNING: Your theme appears to be in the wrong directory for the theme name. The directory name must match the slug of the theme. This theme's correct slug and text-domain is theme-name.
(If this is a child theme, you can ignore this error.)

But I use theme (folder) name themename (without a dash) to avoid of Theme Sniffer plugin namespacing errors.
And I don’t have theme-name in the theme files at all.

Is this a plugin’s mistake or I have to check something else?

Thank you in advance!