Issue with subscript not existing causing crash

Ive stumbled upon a case where my server returned a partially formed body that doesnt include a key.
I see no way in the api to safely access a subscript that may not exist.
Json line 65: `json.jsonData = (jsonData as! [String: Any])[s]!`

My code:
```swift
.onJson { j in
print(j)
if j.stringified?.contains("script") != nil { // added to get around the crash
$script.wrappedValue = j["script"].string
} // added
}
```
Id expect nil as opposed to a crash. I think thats what js would do, just return undefined for a non existing key instead of treating it as an error.
In my xp, though I use force unwraps , I nearly always end up reverting them.