MaterialLoader: Error when loading MeshToonMaterial.

[sir-aureus]

I have a scene I had been working on, which previously worked fine in the editor. As of a recent update, however, it fails to load with the following console errors:

[Error] TypeError: undefined is not an object (evaluating 'material.specular.setHex')
parse (three.module.js:40084)
parseMaterials (three.module.js:41083)
parse (three.module.js:40721)
handleJSON (Loader.js:598)
(anonymous function) (Loader.js:333)

[Error] ReferenceError: Cannot access uninitialized variable.
(anonymous function) (three.module.js:40716)
(anonymous function) (three.module.js:36133)
onImageLoad (three.module.js:36816)

Looking at the code, it looks like the issue stems from an instance of MeshToonMaterial which has a specular parameter in its serialized data, but specular appears to have been removed from the MeshToonMaterial class.

The serialized material in question is:
"{"uuid":"86936197-6FFA-4E61-B36E-9CEC7890DFB1","type":"MeshToonMaterial","color":15986151,"emissive":0,"specular":1118481,"shininess":30,"depthFunc":3,"depthTest":true,"depthWrite":true,"stencilWrite":false,"stencilWriteMask":255,"stencilFunc":519,"stencilRef":0,"stencilFuncMask":255,"stencilFail":7680,"stencilZFail":7680,"stencilZPass":7680}"

[sir-aureus]

Modifying the exported json file of the scene and reimporting is a viable workaround, but not something someone would think of without being able to read and understand the errors and the code that generated the errors.

[Mugen87]

Since r118 the toon material does not support shininess and specular/specularMap anymore, see #19722. These properties were originally present since MeshToonMaterial was derived from MeshPhongMaterial at the beginning.

The removal is noted in the migration guide however it would be possible to handle such import problems more gracefully in MaterialLoader.parse(). E.g. instead of:

if ( json.specular !== undefined ) material.specular.setHex( json.specular );

it could be:

if ( json.specular !== undefined && material.specular !== undefined ) material.specular.setHex( json.specular );

[Mugen87]

BTW: Here is a live example demonstrating the runtime error: https://jsfiddle.net/f2vg501r/