Better messaging for when script attribute parsing fails

There is an issue with script attributes parsing, leading to some errors in editor. Seems like regression since JSON schema been introduced.

Steps to Reproduce

1. Create new blank project
2. Create new script test.js
3. Paste this code into it:

var Test = pc.createScript('test');

Test.attributes.add('chunk', {
    name: 'shader',
    type: 'asset',
    description: 'test'
});

4. In Editor, select test.js asset
5. Hit "Parse" in Inspector few times.

Issue:

Look in console, it failed to update data of that script attributes in underlying data (Observer), due to schema issues. It might be that the path for field it tries to set for attribute - is wrong.

Reproduce the issue with the test.js script from the steps, select it in the Editor Inspector, and press Parse while watching the console. Trace the script-attribute parsing and Observer update path to determine why the schema path fails; done means parsing produces an appropriate message and updates the underlying attribute data correctly.