Add type check in cloneHook

[Huliiiiii]

Close #155.

Hooks might be strings and might be accidentally deconstructed in cloneHook. This will break schemas defined in models.

output of 1.1.4

"application/json": {
  "schema": {
    "0": "a",
    "1": "u",
    "2": "t",
    "3": "h",
    "4": ":",
    "5": ":",
    "6": "s",
    "7": "i",
    "8": "g",
    "9": "n"
  }
}

output of 1.1.3

"application/json": {
  "schema": {
    "$ref": "#/components/schemas/auth::sign"
  }
}

[Huliiiiii]

@SaltyAom Could you please check it?
I'm using version 1.1.3 now, and it causes typebox to throw errors sometimes.