The FILE token does not allow to configure the text that occurs when the file does not exist. It'd be great if this were configurable for cases when this is a non-exceptional occurrence.

Example:

${FILE, path="logs/warnings.html", filenotfoundmessage="No warnings were recorded in %f"}

The current (2.35.1) error message would be implemented using this new parameter as follows:

${FILE, path="logs/warnings.html", filenotfoundmessage="ERROR: File '%f' does not exist"}

This assumes there aren't any more error cases than just 'file not found'. Not sure if there are others. Alternatively, make it possible to mark a $FILE token as e.g. optional=true (so errors are discarded), and to provide a 'default text' like in JENKINS-20324.