Auto-fill does not work with local build of xwsolve.js

[legion80]

After solving the issue I mentioned in #17, I successfully built the .js and .wasm.

But trying to run it I see in console

[Warning] Invalid function pointer called with signature 'iii'. Perhaps this is an invalid value (e.g. caused by calling a virtual method on a NULL pointer)? Or calling a function with an incorrect type, which will fail? (it is worth building your source files with -Werror (warnings are errors), as warnings can indicate undefined behavior which can cause this) (xwsolve.js, line 1)

What is the purpose of auto-fill? Even on your website I can't tell what it does (and FWIW it does not spew this error)