Error issued at system shutdown

When shutting down Windows, CopyQ issues the following message:
```
Command “copyq onExit”
Error: Process crashed
```

Upon looking at CopyQ's log, I see
```
Note [2019-11-01 20:03:38.534] : Command “copyq --clipboard-access monitorClipboard”
Note [2019-11-01 20:03:38.534] : Error: Process crashed
Note [2019-11-01 20:03:38.534] : 1. copyq --clipboard-access monitorClipboard
Note [2019-11-01 20:09:47.941] : Command “copyq --clipboard-access monitorClipboard”
Note [2019-11-01 20:09:47.941] : Error: Process crashed
Note [2019-11-01 20:09:47.941] : 1. copyq --clipboard-access monitorClipboard
Note [2019-11-01 20:09:48.003] : Command “copyq --clipboard-access monitorClipboard”
Note [2019-11-01 20:09:48.003] : Error: Process crashed
Note [2019-11-01 20:09:48.003] : 1. copyq --clipboard-access monitorClipboard
Note [2019-11-01 20:09:50.172] : Command “copyq onExit”
Note [2019-11-01 20:09:50.172] : Error: Process crashed
Note [2019-11-01 20:09:50.172] : 1. copyq onExit
Note [2019-11-01 20:09:50.218] : Command “copyq onExit”
Note [2019-11-01 20:09:50.218] : Error: Process crashed
Note [2019-11-01 20:09:50.218] : 1. copyq onExit
```

The system was turned off and restarted twice during that time.

It looks like one error might be happening when Windows starts (CopyQ is run on startup), and another when Windows is shut down.

I do have CopyQ syncing with an empty sync path to clear the CopyQ data between reboots (see https://github.com/hluk/CopyQ/issues/1063).

**Version, OS and Environment**
- CopyQ Version v3.9.2
- Windows 7 64-bit