Type Alias MergeRecords<Base, Patch>

MergeRecords: {
    [K in keyof Base]: K extends Extract<keyof Patch, string | number>
        ? MergeValue<Base[K], MergeProperty<Patch, K>>
        : string extends K
            ? | Base[K]
            | MergeValue<
                Base[K]
                | undefined,
                Patch[Extract<keyof Patch, string | number>],
            >
            : number extends K
                ? | Base[K]
                | MergeValue<Base[K] | undefined, Patch[Extract<keyof Patch, number>]>
                : Base[K]
} & {
    [K in keyof Patch as K extends string
    | number
        ? K extends keyof Base ? never : K
        : never]?: string extends K
        ? MergeValue<
            Base[Extract<keyof Base, string | number>]
            | undefined,
            Patch[K] | undefined,
        >
        : number extends K
            ? MergeValue<
                Base[Extract<keyof Base, number>]
                | undefined,
                Patch[K] | undefined,
            >
            : Patch[K]
} & {
    [K in keyof Patch as K extends string
    | number
        ? undefined extends MergeProperty<Patch, K> ? never : K
        : never]-?: MergeValue<
        K extends keyof Base ? MergeProperty<Base, K> : undefined,
        Patch[K],
    >
}