BigWig files produce divide by zero in summary view and have "disappearing" data

[cmdcolin]

The BigWig parser does some math to calculate the "average signal" of the bigwig, but this ends up producing a divide by zero error

Line 215 of src/JBrowse/Store/SeqFeature/BigWig/RequestWorker.js

var summaryOpts = {score: sumData/validCnt};

In some cases validCnt is zero in the bigwig.

[cmdcolin]

We could use maxValue instead of sumData/validCnt, and this actually seems more accurate for "spikey" data.

Here are the before with var summaryOpts = {score: sumData/validCnt}; (note the clip markers/infinities where there are divide by zero errors)

Thanks to Scott Cain and Thomas Down for commentary on this

[cmdcolin]

This was reported here http://gmod.827538.n3.nabble.com/Gmod-ajax-Bigwig-disappearing-data-tt4046316.html

[cmdcolin]

Note: Setting a variable scoreType to "maxScore" is now possible in 1.11.6 while helps considerable for wiggle tracks with spiky data. The original divide by zero bug was also fixed.