Add more context in error messages

Signed-off-by: Matthias Beyer <mail@beyermatthias.de>

lib/domain/libimagmail/src/mail.rs

@@ -57,12 +57,17 @@ impl Mail for Entry {
             .context(format_err!("Cannot parse Email {}", mail_file_location.display()))?
             .headers
             .into_iter()
-            .filter_map(|hdr| match hdr.get_key() {
+            .filter_map(|hdr| {
-                Err(e) => Some(Err(e).map_err(Error::from)),
+                match hdr.get_key()
-                Ok(k) => if k == field {
+                    .context(format_err!("Cannot fetch key '{}' from Email {}", field, mail_file_location.display()))
-                    Some(Ok(hdr))
+                    .map_err(Error::from)
-                } else {
+                {
-                    None
+                    Ok(k) => if k == field {
+                        Some(Ok(hdr))
+                    } else {
+                        None
+                    },
+                    Err(e) => Some(Err(e)),
                 }
             })
             .next()
@@ -135,12 +140,17 @@ impl<'a> MailHeader<'a> {
     pub fn get_field(&self, field: &str) -> Result<Option<String>> {
         match self.0
             .iter()
-            .filter_map(|hdr| match hdr.get_key() {
+            .filter_map(|hdr| {
-                Err(e) => Some(Err(e).map_err(Error::from)),
+                match hdr.get_key()
-                Ok(key) => if key == field {
+                    .context(format_err!("Cannot get field {}", field))
-                    Some(Ok(hdr))
+                    .map_err(Error::from)
-                } else {
+                {
-                    None
+                    Ok(key) => if key == field {
+                        Some(Ok(hdr))
+                    } else {
+                        None
+                    },
+                    Err(e) => Some(Err(e))
                 }
             })
             .next()

lib/domain/libimagmail/src/util.rs

@@ -39,8 +39,7 @@ pub(crate) fn get_message_header_at_key<P: AsRef<Path>, K: AsRef<str>>(p: P, k:
         .context(format_err!("Cannot parse Email {}", p.as_ref().display()))?
         .headers
         .into_iter()
-        .filter_map(|hdr| match hdr.get_key() {
+        .filter_map(|hdr| match hdr.get_key().context("Cannot get key from mail header").map_err(Error::from) {
-            Err(e) => Some(Err(e).map_err(Error::from)),
             Ok(key) => {
                 let lower_key = key.to_lowercase();
                 trace!("Test: {} == {}", lower_key, k.as_ref());
@@ -49,11 +48,12 @@ pub(crate) fn get_message_header_at_key<P: AsRef<Path>, K: AsRef<str>>(p: P, k:
                 } else {
                     None
                 }
-            }
+            },
+            Err(e) => Some(Err(e))
         })
         .next()
         .ok_or_else(|| format_err!("'{}' not found in {}", k.as_ref(), p.as_ref().display()))?
-        .and_then(|hdr| hdr.get_value().map_err(Error::from))
+        .and_then(|hdr| hdr.get_value().context("Cannot get value from mail header").map_err(Error::from))
 }
 
 pub(crate) fn get_message_id_for_mailfile<P: AsRef<Path>>(p: P) -> Result<String> {
@@ -77,6 +77,7 @@ pub fn get_mail_text_content<P: AsRef<Path>>(p: P) -> Result<String> {
     ::mailparse::parse_mail(::std::fs::read_to_string(p.as_ref())?.as_bytes())
         .context(format_err!("Cannot parse Email {}", p.as_ref().display()))?
         .get_body()
+        .context("Cannot get body of mail")
         .map_err(Error::from)
 }