Some cleanups

- Remove unused errors.
- Add doc comments.

src/types/errors.rs

@@ -1,4 +1,4 @@
-//! Error typ
+//! Husk Error type
 
 use thiserror::Error;
 

src/types/introducer.rs

@@ -6,7 +6,6 @@ use sequoia_wot as wot;
 use wot::{CertSynopsis, Certification};
 use sequoia_openpgp::{cert::ValidCert, policy::StandardPolicy};
 use sequoia_openpgp::Cert;
-use sequoia_openpgp::Fingerprint;
 
 use crate::types::husk_context::HuskContext;
 use crate::common::crypto;
@@ -15,14 +14,6 @@ use crate::common::crypto;
 pub enum IntroducerError {
     #[error("Unsuitable certificate")]
     UnsuitableCertificate,
-    #[error("Unlimited introducer")]
-    UnlimitedIntroducer,
-    #[error("Invalid domain name: '{0}'")]
-    InvalidDomainName(String),
-    #[error("Certificate {0} contains no usable user id")]
-    NoUserIDs(Fingerprint),
-    #[error("Local trust root is damanged")]
-    RootDamaged,
 }
 
 #[derive(Debug, Clone)]
@@ -33,6 +24,10 @@ pub struct Introducer {
 
 impl Introducer {
 
+    /// Can this introducer potentially introduce `email`?
+    ///
+    /// This check matches the email with the list of domains of the
+    /// introducer.
     pub fn can_introduce(&self, email: &str) -> bool {
         if let Some(regexset) = self.certification.regular_expressions() {
             if regexset.matches_everything() {