Raise an exception when a service call is made on an unavailable entity

I noticed that service calls made on unavailable entities are silently ignored and no exceptions are being raised. Given how far along the HA project is, I was surprised to find out this is the case and noticed (with the custom integrations that I maintain) that, when an entity is unavailable, I can’t raise my own exceptions in service calls to get around this issue. I raised an issue back in July, but it didn’t get any comments or traction.