map.addLayer() of layer having "ref" property throw a TypeError of <whatever_paint_property> undefined

[ggho]

mapbox-gl-js version: 0.28.0

Steps to Trigger Behavior

1. create a map object
2. add a map layer with map.addLayer() that has "ref" property
3. it will throws the TypeError

Codes snippet

//create a map object with source named <some_cource> and source layer named 
//<some_source_layer>
//...

map.addLayer({
    "id": "layer1",
    "type": "line",
    "source": <some_source>,
    "source-layer": <some_source_layer>,
    "paint": {
        "line-opacity": 0.7,
        "line-color": "#000000"
    }
});
// where error was thrown
map.addLayer({
    "id": "layer2",
    "ref": "layer1",
    "paint": {
       //this can be any other paint property
        "line-color": "#fab700"
    }
});

Expected Behavior

No errors thrown.

Actual Behavior

style_layer.js:117 Uncaught TypeError: Cannot read property 'line-color' of undefined
    at i.setPaintProperty (http://api.tiles.mapbox.com/mapbox-gl-js/v0.28.0/mapbox-gl.js:124:2558)
    at new i (http://api.tiles.mapbox.com/mapbox-gl-js/v0.28.0/mapbox-gl.js:124:1000)
    at Function.StyleLayer.create (http://api.tiles.mapbox.com/mapbox-gl-js/v0.28.0/mapbox-gl.js:124:6296)
    at t.addLayer (http://api.tiles.mapbox.com/mapbox-gl-js/v0.28.0/mapbox-gl.js:120:6605)
    at e.addLayer (http://api.tiles.mapbox.com/mapbox-gl-js/v0.28.0/mapbox-gl.js:204:7500)
    at HTMLSelectElement.selector.onchange (http://localhost:8000/:164:26)```

[lucaswoj]

Apologies about this error @ggho. This should have been listed as a breaking change in our release notes. I will update those now.

User-specified refs are no longer supported. If you include all the metadata and layout properties on both layers, the ref will be applied internally.

[lucaswoj]

See #3486

[ggho]

@lucaswoj Thanks for the prompt reply! It explains a lot.

On the other hand, I also realised the "interactive" property is removed without being mentioned in the release note? That one is obvious to notice as error warnings popped out when I used it, the same error message did not happen for "ref" though.

[lucaswoj]

@ggho interactive was removed back in March #1479

[ggho]

@lucaswoj Now I know thanks! I just couldn't find it in the release notes, just wonder if you would add it so others would know easier.

[sdawson26]

This issue has helped me understand why I couldn't get the rich version 9 map to load by means of addLayer() due to the "ref" field.

Are there any future plans to reincorporate this in future versions? We'd like to be able to add streets-v9 without having to put it in the root style and instead add the source after the map initializes.