Add more context in error messages

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

lib/domain/libimaghabit/src/habit.rs

@@ -25,6 +25,7 @@ use chrono::Local;
 use chrono::NaiveDate;
 use failure::Error;
 use failure::Fallible as Result;
+use failure::ResultExt;
 use failure::err_msg;
 
 use crate::iter::HabitInstanceStoreIdIterator;
@@ -257,7 +258,9 @@ impl HabitTemplate for Entry {
 }
 
 fn instance_id_for_name_and_datestr(habit_name: &String, habit_date: &String) -> Result<StoreId> {
-    crate::module_path::new_id(format!("instance/{}-{}", habit_name, habit_date)).map_err(Error::from)
+    crate::module_path::new_id(format!("instance/{}-{}", habit_name, habit_date))
+        .context(format_err!("Failed building ID for instance: habit name = {}, habit date = {}", habit_name, habit_date))
+        .map_err(Error::from)
 }
 
 pub mod builder {

lib/domain/libimaghabit/src/iter.rs

@@ -19,6 +19,7 @@
 
 use failure::Error;
 use failure::Fallible as Result;
+use failure::ResultExt;
 
 use libimagstore::storeid::StoreIdIterator;
 use libimagstore::storeid::StoreIdIteratorWithStore;
@@ -33,11 +34,11 @@ impl Iterator for HabitTemplateStoreIdIterator {
 
     fn next(&mut self) -> Option<Self::Item> {
         while let Some(n) = self.0.next() {
-            match n {
+            match n.context("Error while iterating").map_err(Error::from) {
                 Ok(n) => if n.is_habit_template() {
                     return Some(Ok(n))
                 },
-                Err(e) => return Some(Err(e).map_err(Error::from)),
+                Err(e) => return Some(Err(e)),
             }
         }
         None

lib/domain/libimaghabit/src/util.rs

@@ -21,6 +21,7 @@ use std::ops::BitXor;
 
 use failure::Error;
 use failure::Fallible as Result;
+use failure::ResultExt;
 
 use crate::habit::HabitTemplate;
 use crate::instance::HabitInstance;
@@ -88,6 +89,7 @@ pub fn get_string_header_from_entry(e: &Entry, path: &'static str) -> Result<Str
     e.get_header()
         .read_string(path)?
         .ok_or_else(|| EM::EntryHeaderFieldMissing(path))
+        .context(format_err!("Error while reading header '{}' from '{}'", path, e.get_location()))
         .map_err(Error::from)
 }