.resize() crops image when crop is unnecessary

I’m having trouble with resize function cropping sides of the image when only resize is needed:

// assume expressjs middleware
const resizeTransform = sharp().resize(/* either numbers or undefined-s from querystring */);
const downloadStream = request(req.query.src);
req.pipe(downloadStream).pipe(resizeTransform).pipe(res);

passing along width=200 produces this image:

However passing 199 or 201 produces expected result:

original:

Seems like some strange bug to me. I was expecting to always get a downscaled image in the original aspect ratio. I couldn’t find anything in the documentation regarding controlling the crop. How does one achieves resizing this without cropping, and only having crop when both width and height are present?

I already tried converting to JPEG first, passing both dimensions and playing with .max, .min methods, no luck.

Running node v6.10.2, sharp v0.18.0

[suprMax]

Just checked with v0.18.1 and it works great!

[lovell]

These fixes are in v0.18.1 now available via npm. Please re-open if you’re still having related problems.