Problems handling first point in channel history

[apcarp]

It looks like wave has a problem with displaying the first point in channel history. Prior to the latest jmyapi update, if you request a time span that included the prior point which happened to be the first point in the channel history, you would get null as the data value. Afterwards you get the actual value. If there is no prior data point, and the first data point fall in the requested time span, then you get the value of the first point before the first point happens. Since it's broken for both versions, should push ahead with deploying the new myquery version?

I think the problem is related to this line of code in viewer.js

https://github.com/JeffersonLab/wave/blob/c630bd841ab2367bacfe904611e18e2a9b98d38c/src/main/webapp/resources/js/src/viewer.js#L208C1-L212C1

Here are some links that show the behavior in question.

Currently old jmyapi query and wave display

https://epicsweb.jlab.org/myquery/interval?c=R2O1KMAS&b=2022-06-01&e=2022-07-01&l=&t=graphical&m=&f=&v=&p=on

https://epicsweb.jlab.org/wave/?start=2022-04-01T00%3A00%3A00&end=2022-06-01T13%3A35%3A33&myaDeployment=ops&myaLimit=100000&windowMinutes=30&title=&fullscreen=false&layoutMode=1&viewerMode=1&pv=R2O1KMAS&R2O1KMASlabel=R2O1KMAS&R2O1KMAScolor=%23a6cee3&R2O1KMASyAxisLabel=&R2O1KMASyAxisMin=&R2O1KMASyAxisMax=&R2O1KMASyAxisLog=&R2O1KMASscaler=

New version of jmyapi query and wave display

https://tomcattest1.acc.jlab.org/myquery/interval?c=R2O1KMAS&b=2022-01-01&e=2023-05-01&l=&t=&m=ops&f=&v=&p=on

https://tomcattest1.acc.jlab.org/wave/?start=2022-04-01T00%3A00%3A00&end=2022-06-01T13%3A35%3A33&myaDeployment=ops&myaLimit=100000&windowMinutes=30&title=&fullscreen=false&layoutMode=1&viewerMode=1&pv=R2O1KMAS&R2O1KMASlabel=R2O1KMAS&R2O1KMAScolor=%23a6cee3&R2O1KMASyAxisLabel=&R2O1KMASyAxisMin=&R2O1KMASyAxisMax=&R2O1KMASyAxisLog=&R2O1KMASscaler=

[slominskir]

Adding screenshot of above as new version is only accessible onsite and old version is about to be blown away.

[slominskir]

Possibly related? JeffersonLab/myquery#15