improve formatting of 'show'

src/search.rs

@@ -2,7 +2,7 @@ use std::collections::HashSet;
 use std::iter::Peekable;
 use std::vec::IntoIter;
 
-use anyhow::{Context, Result};
+use anyhow::{bail, Context, Result};
 use clap::ArgMatches;
 use regex::Regex;
 
@@ -27,6 +27,10 @@ pub(crate) fn search_packages(args: &ArgMatches, groups: &HashSet<Group>) -> Res
         }
     }
 
+    if vec.is_empty() {
+        bail!("no packages matching query")
+    }
+
     print_triples(vec);
 
     Ok(())