webmail: fix displaying a message in separate window if there was no …

…known viewmode (text or html or html with externals)

we were sending a zero value for ViewMode, which the frontend js rejected
during parsing.

noticed during testing.

webmail/api.go

@@ -204,8 +204,10 @@ func fromAddrViewMode(tx *bstore.Tx, from MessageAddress) (store.ViewMode, error
 	err = tx.Get(&fas)
 	if err == bstore.ErrAbsent {
 		return settingsViewMode()
+	} else if err != nil {
+		return store.ModeText, err
 	}
-	return fas.ViewMode, err
+	return fas.ViewMode, nil
 }
 
 // FromAddressSettingsSave saves per-"From"-address settings.

webmail/message.go

@@ -181,6 +181,8 @@ func formatFirstLine(r io.Reader) (string, error) {
 }
 
 func parsedMessage(log mlog.Log, m store.Message, state *msgState, full, msgitem bool) (pm ParsedMessage, rerr error) {
+	pm.ViewMode = store.ModeText // Valid default, in case this makes it to frontend.
+
 	if full || msgitem {
 		if !state.ensurePart(m, true) {
 			return pm, state.err