pngRecompress wrong calculation for medium min/max values

[Flohs]

The pngRecompress function fails when passing high values for example min: 93 and max: 99 due to the medium calculation.

I belive it is related to this method. When using min: 40 and max: 99 it works again.

const pngRecompress = async function (min, max, input, output) {
	let temporaryFile;
	let lastResult;
	const results = [];
	const qualities = [max, min];
	const medium = Math.floor((min + max) / 2);
	const mediumMax = Math.round((medium + max) / 2);
	const mediumMin = Math.floor((medium + min) / 2);
	const inputMd5 = md5(input);
        ...

At the moment the png compression fails with the values min: 93 and max: 99

[nhatdo-nfq]

Hi @Flohs , i tested and this is not the cause, this logic just create a array of quality base on min-max that you provided.
Ex: it will like this [ 99, 93, 96, 98, 94 ]
The cause is the quality of the output file after compressing is lower than the minimum quality, or the size of the output file is larger than the original file.
Therefore there is no output file saved, and i will throw the exception

You can see more here: kornelski/pngquant#176 (comment)