TypeError: operator Package[operator] is not a function; with a (temporary) fix

[patarapolw]

I'm submitting a...

[x] Regression (a behavior that used to work and stopped working in a new release)
[x] Bug report  
[x] Temporary fix / possible long term fix

Current behavior

Some filters used in find() does not work as it should with LokiJS or MongoDB. For example,

{$and: [
    {tag: "marked"},
    {$or: [
        {nextReview: {$exists: false}},
        {nextReview: {$in: [null, ""]}},
        {nextReview: {$lt: new Date()}}
    ]}
]}

What is the motivation / use case for changing the behavior?

I am not writing the filter object directly, but by parsing a string with parsimmon https://github.com/patarapolw/zhdiary-app/blob/master/src/backend/db/MongoQParser.ts.

Temporary fix? MongoToFilter function, and use JavaScript's filter in .where().

Environment

LokiDB version: 2.0.0-beta.8 with @lokidb/fs-storage 2.0.0-beta.8
Browser/Node version: Node v11.11.0 Yarn 1.15.2 MacOS