Exception when object field not included in fields list of find or findOne

[johnsoftek]

Bug or feature request

• [X ] Bug
• Feature request

Description of feature (or steps to reproduce if bug)

1. Define a model with {field1: {type: 'number}, field2: {type: object'}}
2. Create a model record
3. Retrieve the model record with fields: ['field1']

Link to sample repo to reproduce issue (if bug)

https://github.com/aams/loopback-connector-sqlite3

Expected result

No crash

Actual result (if bug)

Exception "Uncaught SyntaxError: Unexpected token u in JSON at position 0"

Additional information (Node.js version, LoopBack version, etc)