Vue.js 2.7, "script setup"-approach, defineEmits with composable which needs a emit-function - vuejs2

Question

I am using Vue.js 2.7, I have a (probably TS-only) issue with defineEmits and a self-written composable which needs an emit-function to pass in. The self-written composable should replace a Mixin and is actually too complex, but that's not the problem a like to ask about.
The following does not work.
vue
<script setup lang="ts">
import { defineEmits } from 'vue'; // <- removing this import has no effect
import { useIcomActCompatibility } from '#/composables/compatibility/useIcomActCompatibility';
import { ApiCallParameterType } from '#/services/ApiService';
import { ApiContacts_ListType } from '#/store/types/api/events';
const emit = defineEmits({
'i-do-nothing'(): boolean {
return true;
},
});
const { apiId /* TODO add other necessary stuff */ } = useIcomActCompatibility<
'contacts',
ApiContacts_ListType,
'List'
>({
usedApiId: 'contacts',
usedApiUrl: '/configuration/events/contacts',
usedDataByIdStorePath: 'apiEvents/getApiDataById',
emit, // <- TS2322
sendApiRequest: (_p: ApiCallParameterType): Promise<boolean> => (
console.log('calling dummy sendApiRequest'), Promise.resolve(true)
),
});
</script>
TS2322 is:
Type '(event: 'i-do-nothing') => void' is not assignable to type '(event: string, ...args: any[]) => void'.
Types of parameters 'event' and 'event' are incompatible.
Type 'string' is not assignable to type ''i-do-nothing''.
The code (Vue component) above, beside the TS-Error, could not be created.
Well so far. If I change the code like this?
Vue
<script lang="ts">
import { defineComponent, Ref } from 'vue';
import { useIcomActCompatibility } from '#/composables/compatibility/useIcomActCompatibility';
import { ApiCallParameterType, ApiDataType } from '#/services/ApiService';
import { ApiContacts_ListType } from '#/store/types/api/events';
export default defineComponent({
name: 'HttpServerAct',
setup(props, { emit }): { apiId: Ref<keyof ApiDataType> } {
const { apiId /* TODO add other necessary stuff */ } = useIcomActCompatibility<
'contacts',
ApiContacts_ListType,
'List'
>({
usedApiId: 'contacts',
usedApiUrl: '/configuration/events/contacts',
usedDataByIdStorePath: 'apiEvents/getApiDataById',
emit,
sendApiRequest: (_p: ApiCallParameterType): Promise<boolean> => (
console.log('calling dummy sendApiRequest'), Promise.resolve(true)
),
});
return { apiId };
},
});
</script>
Everything works. My expectation was/is that the 1. version should work also.
What am I doing wrong? I can't imagine that the TS error is solely responsible for this.

Answer 1

Your defineEmits should look like this:
const emit = defineEmits<{
(e: 'i-do-nothing'): boolean;
}>();
https://vuejs.org/guide/typescript/composition-api.html#typing-component-emits