chore: use_clap & clippy

src/pgpcarddecrypt.rs

@@ -1,7 +1,7 @@
 use clap::{ArgMatches, SubCommand, App, Arg};
-use crate::cmd::{Command, CommandError};
 use openpgp_card::DecryptMe;
 use std::collections::BTreeMap;
+use rust_util::util_clap::{Command, CommandError};
 
 pub struct CommandImpl;
 
@@ -56,6 +56,6 @@ impl Command for CommandImpl {
             println!("{}", serde_json::to_string_pretty(&json).unwrap());
         }
 
-        Ok(())
+        Ok(None)
     }
 }