cryptic error when no explicit type is neither in field config and neither in TS return type

[capaj]

  @Field()
  edit(name: string) {
    this.name = name
    return this
  }

Error: Class Function cannot be used as a resolve type because it is not an @ObjectType
    at Object.resolveType (/home/capaj/oss/graphql-repos/typegql/examples/nested-mutation-or-query/node_modules/decapi/src/services/utils/gql/types/typeResolvers.ts:73:11)
    at Object.inferTypeOrThrow (/home/capaj/oss/graphql-repos/typegql/examples/nested-mutation-or-query/node_modules/decapi/src/domains/field/compiler/fieldType.ts:60:10)
    at Object.resolveRegisteredOrInferedType (/home/capaj/oss/graphql-repos/typegql/examples/nested-mutation-or-query/node_modules/decapi/src/domains/field/compiler/services.ts:24:10)
    at compileFieldConfig (/home/capaj/oss/graphql-repos/typegql/examples/nested-mutation-or-query/node_modules/decapi/src/domains/field/compiler/fieldCompiler.ts:26:24)
    at /home/capaj/oss/graphql-repos/typegql/examples/nested-mutation-or-query/node_modules/decapi/src/domains/field/compiler/fieldCompiler.ts:67:35
    at Array.forEach (<anonymous>)
    at getAllFields (/home/capaj/oss/graphql-repos/typegql/examples/nested-mutation-or-query/node_modules/decapi/src/domains/field/compiler/fieldCompiler.ts:56:23)
    at /home/capaj/oss/graphql-repos/typegql/examples/nested-mutation-or-query/node_modules/decapi/src/domains/field/compiler/fieldCompiler.ts:76:35
    at Array.forEach (<anonymous>)
    at Object.compileAllFields (/home/capaj/oss/graphql-repos/typegql/examples/nested-mutation-or-query/node_modules/decapi/src/domains/field/compiler/fieldCompiler.ts:75:21)
npm ERR! code ELIFECYCLE