Page with empty content leads to "This template does not exist" message when viewed in plain mode

Instead of well an blank result...

To reproduce create a page empty or with only white spaces and access it using http://127.0.0.1:8080/xwiki/bin/view/Test/Get?xpage=plain

This is because whatever the issue the result of XWiki#parseTemplate and Utils#parseTemplate take any empty content like a non existing template. This is very wrong, XWiki#parseTemplate should throw exceptions when there is issues.