Calling .addParam on an Asset does not return Asset

[bramski]

Example code:

Stack.Assets('bltfe1acfaa9a6bdb9a').toJSON().addParam('include_dimension', true).fetch().then((asset) => {
    console.debug("Icon Asset", asset);
   });

Expectation:
Get an asset with the debug data on the terminal.

Result:

TypeError: Cannot read properties of undefined (reading 'fetch')

According to the SDK the call to addParam should return an Asset object. Not undefined.