OMEMO not sending messages

[COM8]

Bevor you create a new issue:

- [ x ] I searched for similar issues and did not find one
- [ x ] I'm using the latest version available in the [Windows Store](https://www.microsoft.com/store/apps/9NW16X9JB5WV)

I'm submitting a...:

• Bug report (I searched for similar issues and did not find one)

Current behavior:

If something goes wrong during the OMEMO encryption process, there is no feedback for the user.
The message stays in the sending state and will not be send.
This is also the case for messages send while the account is not connected.

Expected behavior:

Give the user feedback and try resenting messages.

Minimal reproduction of the problem with instructions:

1. Disconnect account
2. Send OMEMO message
3. 💥

Environment:

App Version(s): 
v.0.11.0 <!-- Which version of the App are you using (e.g. v.0.2.0) -->

Windows 10 Version Number: <!-- https://en.wikipedia.org/wiki/Windows_10_version_history -->
- [ x ] 1809
- [ ] 1803
- [ ] 1709
- [ ] 1703
- [ ] 1607
- [ ] 1511
- [ ] 1507
- [ ] Insider Build (build number: )
- [ ] Misc:

Device form factor:
- [ x ] Desktop
- [ x ] Mobile
- [ ] Xbox
- [ ] Surface Hub

Where did you got the APP from?
- [ x ] [Windows Store](https://www.microsoft.com/store/apps/9NW16X9JB5WV)

[COM8]

v.0.15.0.0 should fix this.