I've encountered with some problem with using custom service with custom widget api's method "fetch".
Here I have my custom service
Then I set my manifest.json dependencies field as shown in https://www.jetbrains.com/help/youtrack/standalone/building-custom-widgets.html#
Then I've tried to use method fetch according to https://www.jetbrains.com/help/youtrack/standalone/custom-widgets-API-reference.html#
But got this error
My custom service is definitely visible from widget (checked it with "fetchHub" method to api/rest/services)
P.S. Sorry for bothering if it's impossible to use fetch method with custom services