Always describe the context of the displayed error

src/job.rs

@@ -1190,7 +1190,7 @@ fn perform_job_action(context: &Context, mut job: &mut Job, thread: Thread, trie
         Action::ImexImap => match JobImexImap(context, &job) {
             Ok(()) => Status::Finished(Ok(())),
             Err(err) => {
-                error!(context, "{}", err);
+                error!(context, "Import/export failed: {}", err);
                 Status::Finished(Err(err))
             }
         },

src/message.rs

@@ -1215,7 +1215,7 @@ pub fn set_msg_failed(context: &Context, msg_id: MsgId, error: Option<impl AsRef
         }
         if let Some(error) = error {
             msg.param.set(Param::Error, error.as_ref());
-            error!(context, "{}", error.as_ref());
+            error!(context, "Message failed: {}", error.as_ref());
         }
 
         if sql::execute(