.toString() coerces null to string:null

[rkaw92]

Simple test case:

'use strict';

const Query = require('rql/query').Query;
const testPredicate = new Query().eq('foo', null);
console.log(testPredicate.toString());

Expected output:
eq(foo,null)

Actual output:
eq(foo,string:null)

Going to fix this in greatcare/rql, so that null values no longer get coerced. This is probably due to the special-case treatment of null in the first lines of query's encodeValue.

[wshager]

@neonstalwart I see no problem with this fix, could you merge it? Who else has write permission nowadays?

[neonstalwart]

I'm uncertain about my status to contribute to open source. I believe it's probably ok for me to merge something like this (since I'm not the author) but since I'm not certain I'd rather not. I know I can get permission to contribute code I've authored by having my contributions reviewed and approved by my employer before contributing but that extra step is just enough of a burden to make it more effort than I have the time and energy for right now. I'm not sure who else could merge it.