Uncaught SyntaxError missing ( after argument list

[Flachzange]

I was wondering why my frontend page kept being empty (index.html loaded but without data). As I did a lot of infrastructure changes I ignored it first.

Yesterday, I started digging and found the reason to be unescaped characters in pethubconfig.json. To be precise:

"Custom_Modes": "['Threeseconds', 'Metalmode2', 'Extendedrange']"

The loading function for the config sits in

pethublocal/pethublocal/frontend.py

Line 194 in d3fc739

return web.Response(content_type='application/javascript', body='pethubconfig=JSON.parse(\'' + json.dumps(request.app['pethubconfig']) + '\');')

and this then obviously results in a

Uncaught SyntaxError missing ( after argument list

A fix is to remove the JSON.parse entirely as you read JSON into JS which does not require any additional parsing:

return web.Response(content_type='application/javascript', body='pethubconfig=' + json.dumps(request.app['pethubconfig']))

This populates the frontend again without any errors.