Fix assertion when referencing a global within its own initializer

[dcodeIO]

This should fix #1186 by emitting a Cannot find name 'x'. diagnostic instead of aborting.

[MaxGraey]

btw with shadowing it also should emit compile error in TS and runtime ref error in JS (ReferenceError: Cannot access 'd' before initialization)

let d = 1;
export function testLet2(): i32 {
  let d = (d = 2, 3);
  return d;
}

But currently compile without any issues: https://webassembly.studio/?f=ym35gg4wwm

TS:

let d = 1;
export function testLet2(): number {
  d = 2;
  // let d = 3;  // uncomment this will cause compiler error in TS
  return d;
}

[dcodeIO]

Hmm, yeah, that complicates things, so might need a proper mechanism.

[dcodeIO]

A proper fix for some of this will require some sort of pre-pass binding variables to scopes before compiling a scope's statements. While not exactly JS currently, this seems rather low priority and I'm fine with

function foo(): void {
  a = 1;
  var a: i32;
}

erroring because it's bad code anyway. Referencing a global from the outer scope there is unfortunate, though.

[MaxGraey]

I agree. Also this quite antistatic case. So just printing proper error for all cases will be fine