Add some error checking in parsing

.gdbinit

@@ -2,3 +2,4 @@ break rust_panic
 break core::option::expect_failed::h4927e1fef06c4878
 break core::panicking::panic
 break libcore/panicking.rs:58
+break libcore/result.rs:945

melib/src/mailbox/backends/maildir.rs

@@ -216,7 +216,9 @@ impl MaildirType {
                                 Envelope::from_token(Box::new(BackendOpGenerator::new(Box::new(
                                     move || Box::new(MaildirOp::new(e_copy.clone())),
                                 )))) {
-                                e.populate_headers();
+                                if e.populate_headers().is_err() {
+                                    continue;
+                                }
                                 local_r.push(e);
                             }
                         }

melib/src/mailbox/email/mod.rs

@@ -23,6 +23,7 @@ pub mod attachments;
 pub mod parser;
 
 pub use self::attachments::*;
+use error::{MeliError, Result};
 use mailbox::backends::BackendOpGenerator;
 
 use std::cmp::Ordering;
@@ -249,14 +250,14 @@ impl Envelope {
         Some(e)
     }
 
-    pub fn populate_headers(&mut self) -> () {
+    pub fn populate_headers(&mut self) -> Result<()> {
         let mut operation = self.operation_token.generate();
-        let headers = match parser::headers(operation.fetch_headers().unwrap()).to_full_result() {
+        let headers = match parser::headers(operation.fetch_headers()?).to_full_result() {
             Ok(v) => v,
-            _ => {
+            Err(e) => {
                 let operation = self.operation_token.generate();
                 eprintln!("error in parsing mail\n{}", operation.description());
-                return;
+                return Err(MeliError::from(e));
             }
         };
 
@@ -324,6 +325,7 @@ impl Envelope {
                 self.set_datetime(d);
             }
         }
+        Ok(())
     }
     pub fn date(&self) -> u64 {
         self.timestamp
@@ -362,7 +364,9 @@ impl Envelope {
             Err(_) => {
                 let operation = self.operation_token.generate();
                 eprintln!("error in parsing mail\n{}", operation.description());
-                panic!()
+                let error_msg = b"Mail cannot be shown because of errors.";
+                let mut builder = AttachmentBuilder::new(error_msg);
+                return builder.build()
             }
         };
         let mut builder = AttachmentBuilder::new(body);

melib/src/mailbox/email/parser.rs

@@ -500,6 +500,9 @@ named!(pub address_list<String>, ws!(do_parse!(
 named!(pub phrase<String>, ws!(do_parse!(
         list: many0!(alt_complete!( encoded_word_list | ascii_token)) >>
         ( {
+            if list.len() == 0 {
+               String::new()
+            } else {
             let string_len = list.iter().fold(0, |mut acc, x| { acc+=x.len(); acc }) + list.len() - 1;
             let list_len = list.len();
             let mut i = 0;
@@ -512,6 +515,7 @@ named!(pub phrase<String>, ws!(do_parse!(
                 }
                 acc
             })
+            }
         } )
 
        )));