toJSON() repeats pending updates to nested keys

[mstniy]

New Issue Checklist

• I am not disclosing a vulnerability.
• I am not just asking a question.
• I have searched through existing issues.
• I can reproduce the issue with the latest versions of Parse Server and the Parse JS SDK.

Issue Description

If there are pending updates to nested fields, the object returned by toJSON() is corrupted.

Steps to reproduce

a = new Parse.Object("MyObject");
a.set('obj', {});
await a.save();
a.set('obj.a', 0);
console.log(a.toJSON());

Actual Outcome

Prints an object with the keys {obj: {a: 0}, 'obj.a': 0}

Expected Outcome

Should print roughly {obj: {a: 0}}

Environment

Server

• Parse Server version: irrelevant
• Operating system: Ubuntu 20.04
• Local or remote host (AWS, Azure, Google Cloud, Heroku, Digital Ocean, etc): local

Database

• System (MongoDB or Postgres): MongoDB
• Database version: 5.0.6
• Local or remote host (MongoDB Atlas, mLab, AWS, Azure, Google Cloud, etc): local

Client

• Parse JS SDK version: alpha (d084ac9be058d9b13f8ac2bbf04615f76dc2800d)

Logs

[parse-github-assistant]

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[mtrezza]

Did you mix expected and actual outcome?

[mstniy]

Whoops. Fixed.