Add deprecation warning to parseQuery

This deprecation warning is intended to alarm loader authors that passing an object to parseQuery and then modifying it might lead to unintended behavior.

#56

index.js

@@ -1,5 +1,7 @@
 var JSON5 = require("json5");
 var path = require("path");
+var util = require("util");
+var os = require("os");
 var assign = require("object-assign");
 var emojiRegex = /[\uD800-\uDFFF]./;
 var emojiList = require("emojis-list").filter(function(emoji) {
@@ -65,7 +67,11 @@ exports.parseQuery = function parseQuery(query) {
 	};
 	if(!query) return {};
 	if(typeof query !== "string")
-		return query;
+		return (util.deprecate(function () {},
+		"loaderUtils.parseQuery() just received a value type of " + typeof query +
+		" which can be problematic, see https://github.com/webpack/loader-utils/issues/56" + os.EOL +
+		"parseQuery() will be replaced with getOptions() in the next major version of loader-utils."))(),
+		query;
 	if(query.substr(0, 1) !== "?")
 		throw new Error("a valid query string passed to parseQuery should begin with '?'");
 	query = query.substr(1);