Properties with type: 'json' do not use their fieldName(s) value

[bravely]

Describe the bug
The title really says it all.

Some extra detail, to aid in fixing:

• This line is where the key for the given field is modified to apply JSON-lookup syntax.

Stack trace
This is misleading, just demonstrates what happens. The entity below has two @Propertys, one of which is dataHash(a string type), and the other as internalData(a JSON type).

error: select "e0".* from "datapoints" as "e0" where "e0"."data_hash" = 'lol' and "internalData"->>'title' = NULL - column "internalData" does not exist

      at Parser.parseErrorMessage (node_modules/pg-protocol/src/parser.ts:357:11)
      at Parser.handlePacket (node_modules/pg-protocol/src/parser.ts:186:21)
      at Parser.parse (node_modules/pg-protocol/src/parser.ts:101:30)
      at Socket.stream.on (node_modules/pg-protocol/src/index.ts:7:48)

To Reproduce
Steps to reproduce the behavior:

1. Create an entity in a Postgres-backed Mikro-ORM project with a JSON property and a different property name than the column it points at. Easiest way to do this is: @Property({type: 'json'}) aField: Record<string, any> = {}
2. Insert some data into that field in the DB.
3. Run a query, any query(where, select, sort, etc) on a property in that field. I have an example above.

Expected behavior
The query to target the appropriate column.

Additional context
None

Versions

Dependency	Version
node	10
typescript	4.2
mikro-orm	4.4.4
pg	8.3.2

[bravely]

Also as a sidenote, it's possible this is also causing the bug for why JSON-queries that filter for null come out as = null instead of is null(as the former will always return empty).