Updating time and date in wit-ai weather example - node.js

Question

I am trying to extend the wit-ai weather example by adding wit/datetime to the mix.
For example a user might type "How cold will it be in Berlin in 1 hour?" and the weather bot will bring back the data for the weather in 1 hour in Berlin.
So far this works, but when I try to setup missingDate in order to ask the date if it's missing it behaves kind of funny.
A dialogue would be:
- How cold will it be in Berlin?
- In what time?
- In 1 hour.
Instead, after the 1 hour step, I get asked again for the location which is in the context, but instead is triggered again.
My action is named getForecast({context, entities}) and I have defined it as below:
actions:
[...],
getForecast({ context, entities }) {
console.log(`The current context is: ${JSON.stringify(context)}`);
console.log(`Wit extracted ${JSON.stringify(entities)}`);
// extract entity
var location = firstEntityValue(entities, "location");
var date = firstEntityValue(entities, "datetime");
// if the entity exists, do a remote weather call.
if (date) {
context.date = date;
delete context.missingDate;
} else {
context.missingDate = true;
delete context.date;
delete context.forecast;
}
if (location) {
context.forecast = '38 degrees';
context.location = location;
delete context.missingLocation;
} else {
context.missingLocation = true;
delete context.forecast;
}
// return the context object
return Promise.resolve(context);
}