this took me a while to figure out. for about a week i try to google a problem i have been having. i was able to fetch the json data from a URL and show the whole object on the HTML template using the following code:

    <pre >
        {{question| json}}

I would get all the JSON object displayed on the screen, the object would look something like this:

"Question": "This is the question"

then i would try to just show the question property with the following code:

    <pre >

Then i would get this error:

Runtime Error. Error in HomePage - caused by: self.context.question is undefined

to fix this all i had to do is change a variable in home.ts
FROM : public question: any;
TO: public question: any = {};

So what does this error simple mean? it means that the object property did not exists. it could also mean, as in my case that you not initially declared the variable as an object and instead as just a string.