fix(parser): ensure data is piped when using '-' argument
Fixes#1626.
Check to see if data was actually piped to yay, otherwise it will hang
forever. This error will give users better feedback of how to use the
'-' argument (it is also the same exact error pacman throws for invalid
piped data).
Two tests were added. However, I didn't know how to add a test for the
actual part that detects whether data was piped or not (which is
essentially what this commit adds).