[77] Move no theme.json file found error message so it displays correctly.

[jordanharris-6]

77 - This PR moves the ThemerNotice component into a position so that it shows when no theme.json file is found.

Change Log

• Adds a new if statement to check for the theme.json file
• Removes checks from the last return statement as these are done further up now.

Steps to test

Go to the style editor and check themer works
Remove or rename theme.json in the theme folder
Refresh the page
The error cannot read the file "theme.json" should show

Screenshots/Videos

http://bigbite.im/v/vg2HSM

Checklist:

• My code follows the style guidelines of this project
• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• My changes generate no new warnings
• Any dependent changes have been merged and published in downstream modules

[g-elwell]

Great catch, thanks for looking into this one!