use Instance type and optimize

packages/server/src/schema/uuid/abstract-uuid/resolvers.ts

@@ -32,7 +32,7 @@ import {
 import { createEvent } from '~/schema/events/event'
 import { SubjectResolver } from '~/schema/subject/resolvers'
 import { decodePath, encodePath } from '~/schema/uuid/alias/utils'
-import { Resolvers, QueryUuidArgs, TaxonomyTermType } from '~/types'
+import { Instance, Resolvers, QueryUuidArgs, TaxonomyTermType } from '~/types'
 import { isDefined } from '~/utils'
 
 export const UuidResolver = createCachedResolver<
@@ -380,13 +380,16 @@ async function resolveUuidFromDatabase(
           : null
       const subjectName = subject ? toSlug(subject.name) : 'serlo'
 
-      let fallbackTitle: string = baseUuid.entityType
-      if (baseUuid.entityInstance === 'de') {
-        if (fallbackTitle === 'text-exercise') fallbackTitle = 'aufgabe'
-        else if (fallbackTitle === 'text-exercise-group') fallbackTitle = 'aufgabengruppe'
-      }
-
-      const slugTitle = toSlug(baseUuid.entityTitle ?? fallbackTitle)
+      const slugTitle = baseUuid.entityTitle
+        ? toSlug(baseUuid.entityTitle)
+        : (() => {
+            if (baseUuid.entityInstance === Instance.De) {
+              if (baseUuid.entityType === 'text-exercise') return 'aufgabe'
+              if (baseUuid.entityType === 'text-exercise-group')
+                return 'aufgabengruppe'
+            }
+            return baseUuid.entityType
+          })()
 
       const entity = {
         ...base,