Some triggers unavailable and some service methods raise an exception (example of getRoundInfo)

[c0nsol3]

I'm trying to get information about a round using getRoundInfo method. I've tried calling that function via triggers and by injecting a service and calling the getRoundInfo method that way. Both approaches failed. I'm having difficulty understanding why some service methods aren't callable while I'm able to see them being used elsewhere in core?

Using triggers.

const roundInfo = await this.triggers.call("getRoundInfo", {});
// fails due to trigger not existing

Using injected service

@Container.injectable()
export default class Service {
    @Container.inject(Container.Identifiers.DposState)
    @Container.tagged("state", "blockchain")
    private readonly dposState!: Contracts.State.DposState;

    start() { 
        const roundInfo = await this.dposState.getRoundInfo();
    }
}

Results in the following error:

AssertionException: Expected value which is "non-null and non-undefined".
    at assertType (/home/derp/Documents/projects/ark/core/packages/core-kernel/dist/utils/assert.js:7:15)
    at Object.defined (/home/derp/Documents/projects/ark/core/packages/core-kernel/dist/utils/assert.js:30:16)
    at DposState.getRoundInfo (/home/derp/Documents/projects/ark/core/packages/core-state/dist/dpos/dpos.js:21:36)
    at Object.handle (/home/derp/Documents/projects/ark/core/plugins/arkdelegates-plugin/dist/bot.js:30:56)
    at processTicksAndRejections (internal/process/task_queues.js:95:5)
    at async Promise.all (index 14)
    at async MemoryEventDispatcher.dispatch (/home/derp/Documents/projects/ark/core/packages/core-kernel/dist/services/events/drivers/memory.js:153:9)

[c0nsol3]

I've found another way to get roundInfo, but I'd still like to understand why approaches in the original comment didn't work so I'll be able to better understand how this service and trigger interface is meant to be working and for which things.

For anyone curious how I manage to get round info:

import { Container, Contracts, Utils as AppUtils } from "@arkecosystem/core-kernel";

@Container.injectable()
export default class Service {
    @Container.inject(Container.Identifiers.StateStore)
    private readonly stateStore!: Contracts.State.StateStore;

    start() { 
        const block = this.stateStore.getLastBlock();
        const roundInfo = AppUtils.roundCalculator.calculateRound(block.data.height);
    }
}