stdx.data.json - enhancement suggestions

[Laeeth Isharc via Digitalmars-d-learn]

It doesn't like it.  Any thoughts ?

lexer.d(257): Error: safe function 
'stdx.data.json.parser.JSONLexerRange!(MapResult!(__lambda3, 
Result), cast(LexOptions)0, __lambda31).JSONLexerRange.empty' 
cannot call system function 
'app.lookupTickers.MapResult!(__lambda3, Result).MapResult.empty'

string[2][] lookupTickers(string dataSource,string[] searchItems)
{
	import stdx.data.json;
	import std.conv:to;
	import std.algorithm:canFind,countUntil,joiner,map;
	import std.string:toLower;
	bool found=false;
	bool checkedCode=false;
	bool checkedName=false;
	string[2][] ret;
	string buf;
	auto filename="../importquandl/"~dataSource~".json";
	//auto data=cast(string)std.file.read(filename);
	auto data = File("fileName")
		.byChunk(100*1024 * 1024) //1 MB. Data cluster equals 1024 * 4
		// .map!(ch => ch.idup)
		.joiner
		.map!(b => cast(char)b);
	auto range1=parseJSONStream(data);
}