If an SVG file with mouse is created, embedded into a web page and then opened in a browser, parseSettings() in gnuplot_svg() in gnuplot_svg.js tries to convert the commented JavaScript with statements line gnuplot_svg.setting = (value); into JSON.
However, the comment fragment contains more newlines than expected and after all regexes are applied has double commas, commas in the beginning and commas in the end; causing JSON.parse() to fail, breaking all subsequent JavaScript.
I would like to submit a patch fixing this, and for this purpose creating this bug.
I am not able to reproduce this. Is your browser not able to display the SVG on-line demos?
https://gnuplot.sourceforge.net/demo_svg_6.0/
What O/S and browser are you using?
I would be happy to look a patch, but it will be hard to test and evaluate if I can't reproduce the problem.