Include QID and title in error mails

Closes: #31

app.py

@@ -400,6 +400,7 @@ def get_institution(entity, other):
 @app.route("/item/Q<int:item_id>")
 def item_page(item_id):
     qid = f'Q{item_id}'
+    g.qid = qid
     item = artwork.Artwork(qid)
     from_redirect = qid in session and session.pop(qid) == 'from redirect'
     entity = mediawiki.get_entity_with_cache(qid, refresh=not from_redirect)
@@ -423,6 +424,7 @@ def item_page(item_id):
         label = label_and_language['label']
     else:
         label = None
+    g.label = label
     other = get_other(item.entity)
 
     people = human.from_name(label) if label else None

depicts/error_mail.py

@@ -1,15 +1,23 @@
 import logging
 from logging.handlers import SMTPHandler
 from logging import Formatter
-from flask import request
+from flask import request, g
 
 PROJECT = 'depicts'
 
 class MatcherSMTPHandler(SMTPHandler):
     def getSubject(self, record):  # noqa: N802
-        return (f'{PROJECT} error: {record.exc_info[0].__name__}'
-                if (record.exc_info and record.exc_info[0])
-                else f'{PROJECT} error: {record.pathname}:{record.lineno:d}')
+        subject = (f'{PROJECT} error: {record.exc_info[0].__name__}'
+                   if (record.exc_info and record.exc_info[0])
+                   else f'{PROJECT} error: {record.pathname}:{record.lineno:d}')
+
+        if qid := getattr(g, 'qid', None):
+            subject += f' {qid}'
+
+        if label := getattr(g, 'label', None):
+            subject += f': {label}'
+
+        return subject
 
 class RequestFormatter(Formatter):
     def format(self, record):