Dashboard: Get error under console when removing gadget

Description

Step to reproduce

1. Access the daily site: http://sh-daily.ep.se/release-9-8-2-alloy/.
2. Log in.
3. Go to the Dashboard page.
4. Add a gadget (for example, the Forms Viewer) to an existing tab.
5. Remove that gadget.

Expected: You remove the gadget successfully.
Actual: Although you remove the gadget successfully, you get an error under the console:

POST http://sh-daily.ep.se/release-9-8-2-alloy/EPiServer/shell/Stores/component/

500 Internal Server Error
264ms
dojo.js (line 15)
"NetworkError: 500 Internal Server Error - http://sh-daily.ep.se/release-9-8-2-alloy/EPiServer/shell/Stores/component/"
/releas...ponent/
[object Object]


...rumentRejected&&_2ed.length===0){_2f1.instrumentRejected(_2ee,false,_2ef,_2f0);}...