Analyse following RPM build log snippet. Describe contents accurately, without speculation or suggestions for resolution.            
Your analysis must be as concise as possible, while keeping relevant information intact.
Snippet: 
- ./_site/explainery/elektrifikace-dopravy.html

  *  Build error (line 370)

     No item with slug 57-doprava-ve-meste
It shows there was an error while building file "./_site/explainery/elektrifikace-dopravy.html" on line 370.