Json transform error

/usr/local/app/src/dodis-normalizer-transformer.ts:27
        const data = JSON.parse(chunk.res.body);
                          ^
SyntaxError: Unexpected token < in JSON at position 0
    at JSON.parse (<anonymous>)
    at DodisNormalizerTransformer._transform (/usr/local/app/src/dodis-normalizer-transformer.ts:27:27)
    at DodisNormalizerTransformer.Transform._read (_stream_transform.js:190:10)
    at DodisNormalizerTransformer.Transform._write (_stream_transform.js:178:12)
    at doWrite (_stream_writable.js:415:12)
    at writeOrBuffer (_stream_writable.js:399:5)
    at DodisNormalizerTransformer.Writable.write (_stream_writable.js:299:11)
    at MagpieTransformer.ondata (_stream_readable.js:709:20)
    at MagpieTransformer.emit (events.js:198:13)
    at addChunk (_stream_readable.js:288:12)
    at readableAddChunk (_stream_readable.js:269:11)
    at MagpieTransformer.Readable.push (_stream_readable.js:224:10)
    at MagpieTransformer.Transform.push (_stream_transform.js:151:32)
    at Request.MagpieTransformer._request [as _callback] (/usr/local/app/node_modules/magpie/src/magpie-transformer.ts:113:22)
    at Request.self.callback (/usr/local/app/node_modules/request/request.js:185:22)
    at Request.emit (events.js:198:13)