INFER does not work on single element JSON docs

Problem

A document with single JSON element ( raw JSON types) is valid JSON, for example a string or array or a number:

5

"raw string"

["array","of","raw","values",12345,true]

true

Unfortunately INFER doesn't handle them and produces an empty schema. 

Steps to reproduce

1. Insert a number of single JSON Element documents (ensure that the Data type is set correctly to JSON)
2. Run INFER