Error devalue.dist:devalue.umd in walk error - Cannot stringify arbitrary non-POJOs

[simllll]

Version

v2.1.0

Reproduction link

[http://not able to extract the issue](http://not able to extract the issue)

Steps to reproduce

I have a express app that calls nuxt.renderRoute for speicfic routes. Somehow, I wasn't able to track it down, I get the following error for logged in users:
Error: Cannot stringify arbitrary non-POJOs
/var/app/current/node_modules/devalue/dist/devalue.umd.js in walk at line 44:31
/var/app/current/node_modules/devalue/dist/devalue.umd.js in null. at line 49:72
Array.forEach
/var/app/current/node_modules/devalue/dist/devalue.umd.js in walk at line 49:40
/var/app/current/node_modules/devalue/dist/devalue.umd.js in null. at line 49:72
Array.forEach
/var/app/current/node_modules/devalue/dist/devalue.umd.js in walk at line 49:40
/var/app/current/node_modules/devalue/dist/devalue.umd.js in null. at line 49:72
Array.forEach
/var/app/current/node_modules/devalue/dist/devalue.umd.js in walk at line 49:40
/var/app/current/node_modules/devalue/dist/devalue.umd.js in null. at line 49:72
Array.forEach
/var/app/current/node_modules/devalue/dist/devalue.umd.js in walk at line 49:40
/var/app/current/node_modules/devalue/dist/devalue.umd.js in devalue at line 53:5
/var/app/current/node_modules/nuxt/lib/core/renderer.js in Renderer.renderRoute at line 364:50

This issue first occured in nuxt 2, and the initial line that triggers it is the following one in renderRoute:
const serializedSession = window.__NUXT__=${devalue(context.nuxt)};

as far as I understand that means that in context.nuxt is a variable that has function in it? But why? Can we ignore the function? Or how can I get rid of it?

What is expected ?

Should render all routes, even if context.nuxt (what is it actually?), has a function in it

What is actually happening?

Error: Cannot stringify arbitrary non-POJOs

_{This bug report is available on Nuxt community (#c7909)}

[simllll]

Indeed I just found out that under some circumstances req.session.flash is set, by the "flash"-express middleware. https://github.com/expressjs/flash

This middleware puts a function into the session. I can imagine there are some other usecases like this too (even though I would agree that this session middleware is not a very nice one).

I suggest that serializedSessino should not crash, even when there is a functino in it. It should just strip all elements away which it can not serialize... (and put a warning to the console?).

[ghost]

This bug-report has been cancelled by @aldarund.

dupe of #4026
PR with fix #4046

[lock]

This thread has been automatically locked since there has not been any recent activity after it was closed. Please open a new issue for related bugs.