missing function: _ZN6il2cpp2os12MarshalAlloc8AllocateEj UnityLoader.js:1:8039

Question

I am developing a system to pay via PayPal. I experience this problem when I try to "checkout" and please help me if you can think of any solution for this problem.

Everything perfectly works on Windows build but fails when it try it on WebGL.

Here's the code that I wrote

github.com/Dzimmy/PayPal-payment-system

Here's snapshot from the first error

Here's snapshot from the second error