Grid to pdf fails in PHP 7.4

/gridPdfGenerator.php at 149 : A non-numeric value encountered
For versions of PHP > 7.0

I pulled files from here:
https://docs.dhtmlx.com/grid__data_export.html?_ga=2.97903903.1044814387.1593133974-401393102.1593133974

Is there an updated version that fixes this error?

Unfortunately there is no newer version of the grid export supporting php7+.
All I can suggest is to use the php5, or try to modify the export service manually.
The sources are available on github: