Does the app in question have a DESCRIPTION file? If so, try running read.dcf() on it and if it gives you a similar error, you have to fix the line that contains 'Unnamed repository; ...'
It could also be that one of the packages your app depending on has a malformed DESCRIPTION file. You could try hunting down which one is it by doing
read.dcf(system.file("DESCRIPTION", package = "pkgName", mustWork = TRUE))
on the package dependencies and seeing if any throw a similar error.
Also, it might be interesting to know if the app runs ok without shiny server?