Json secrets not being displayed on UI when a value is null

[CodeLover254]

Describe the bug
On Vault 1.16.2 display of json secrets breaks when a value in the json object is null. On inspection of the console, I realized that the javascript code was failing with the error. Uncaught (in promise) TypeError: Cannot convert undefined or null to object
at Function.keys ()

To Reproduce
Steps to reproduce the behavior:

1. Create a kv secret engine then press the add secret button.
2. Toggle the json switch to on, give your secret a name and inside the text area add the following json

{
   "key":null,
}

3. Click the save button. The secret should be saved but cannot be displayed on the //details?version=1 page as long as the json switch is toggled to on.

Expected behavior
The json content should display in the details page regardless of a value in the json being null.

Environment:

• Vault Server Version (retrieve with vault status): 1.16.2
• Vault CLI Version (retrieve with vault version): Vault v1.16.2 (c6e4c2d)
• Server Operating System/Architecture: Ubuntu 20.04 arm64

Vault server configuration file(s):

ui = true
disable_mlock = true

storage "raft" {
  path = "/opt/vault/data"
  node_id="node1"
}

api_addr = "http://127.0.0.1:8200"
cluster_addr="https://127.0.0.1:8201"

listener "tcp" {
  address = "127.0.0.1:8200"
  tls_disable = 1
}

[timonych]

Also reproduced on 1.16.1

[Monkeychip]

Fixed per the linked prs.