[demo] Can't submit examples (error 500) about getrector-com

[samsonasik]

@liarco It seems fixed now by revert #441 (comment)

Thank you @TomasVotruba

[liarco]

Thank you, now it works! :)

[TomasVotruba]

Thanks for reporting.

See #441

[samsonasik]

@TomasVotruba I tested locally with docker, and it seems working ok, with tweak:

1. First run, manifest.json is not generated, so I commented it
2. Run it, show the page after submit

3. next, re-enable commented manifest.json, and it show the page with css enabled

[samsonasik]

@TomasVotruba I think manifest.json is unrelated for this, if the file not exists and it is enabled, even the home page will already error.

On this case, only demo page that show the error on getrector.org/demo.