Extract non-string value from response object - azure-api-management

Question

In APIM I want to get an OAuth token before calling the back-end and store it in the APIM cache.
I manage to get the OAuth token.
I wish to store my token in the cache for this I need a duration.
Extracting the duration from the response body is my issue.
First I extract the token and duration to save these in variables.
Then the variables are used to store a value in the cache.
When extracting the integer value of "expires_in" it fails.
Response object:
{
"access_token": "accesstokenresponse",
"token_type": "bearer",
"expires_in": 3600
}
extracting data and put in variables:
<set-variable name="bearer-token"
value="#(((IResponse)context.Variables["response"]).Body.As<JObject>()["access_token"].ToString())" />
<set-variable name="expires-in"
value="#(((IResponse)context.Variables["response"]).Body.As<JObject>(preserveContent: true)["expires_in"].ToString())" />
storing in cache:
<cache-store-value key="OAuthKey"
value="#((string)context.Variables["bearer-token"])"
duration="#((int)context.Variables["expires-in"])" />
Extracting the "expires_in" results in an Object reference not set to an instance of an object.
set-variable (153.612 ms)
{
"messages": [
{
"message": "Expression evaluation failed.",
"expression": "((IResponse)context.Variables[\"response\"]).Body.As<JObject>(preserveContent: true)[\"expires_in\"].ToString()",
"details": "Object reference not set to an instance of an object."
},
"Expression evaluation failed. Object reference not set to an instance of an object.",
"Object reference not set to an instance of an object."
]
}

Answer 1

Try to maintain the value of Objects using (preserveContent: true) on first line as well, thus:
value="#(((IResponse)context.Variables["response"]).Body.As<JObject>(preserveContent:true)["access_token"].ToString())" />
Let me know if it's solved.