matches

Returns true if this matches domain and code, false otherwise.

In particular, when this is null, false will be returned.

If domain contains a `FAILED` (or otherwise generic) error code, you should generally not check for it explicitly, but should instead treat any not-explicitly-recognized error code as being equivalent to the `FAILED` code. This way, if the domain is extended in the future to provide a more specific error code for a certain case, your code will still work.

Parameters:

this	a Error
domain	an error domain
code	an error code

Returns:

whether this has domain and code