fix(backfill): openIssuesTotal under-counts when open PRs are subtracted from GraphQL issues - #162

Property '__typename' does not exist on type '{ number?: number; title?: string; state?: string; url?: string; body?: string | null; createdAt?: string | null; updatedAt?: string | null; authorAssociation?: string | null; author?: { login?: string | null; } | null; labels?: { ...; } | null; }'.