I am using the antimatter theme that comes with the prepackaged blog package.
If a page has an image in it (ie an image is placed in the same folder as the .md page file) and you remove or change the image file name, the page will report an ERROR.
I figured it out that if you delete or change the image, you need to resave the .md file, in order not to get an ERROR report.
But you need to resave the md file even if you make no changes to its content. I guess a change the in save timestamp of the file is used to re-scan the page folder for images.
Please change the code of the theme so that if an image is deleted or changed, the page still displays correctly without having to save the .md file again.