Print better compiler error for duplicate identifiers

[MaxGraey]

class Foo {
  field: i32;
  field: i64;
}
const foo = new Foo();

But this should be valid:

class Foo {
  field: i32;
  static field: i64;
}

Expected compiler error:

Dublicate identifier 'field'

Actual:

ERROR: AssertionError: assertion failed

[DanielRX]

Me and @karzanbotani are currently working this fix now, is there a set way you want it to error?

This is the current message we have:

ERROR: AssertionError: Duplicate instance member: 'field' in file 'test.ts', line: 3 column: 15
    at assert (*/assemblyscript/std/portable/index.js:184:9)
    at Compiler.compileTopLevelStatement (*/assemblyscript/src/compiler.ts:1635:11)
    at Compiler.compileFile (*/assemblyscript/src/compiler.ts:759:12)
    at Compiler.compile (*/assemblyscript/src/compiler.ts:366:14)
    at Object.compileProgram (*/assemblyscript/src/index.ts:146:41)
    at stats.compileTime.measure (*/assemblyscript/cli/asc.js:591:31)
    at measure (*/assemblyscript/cli/asc.js:929:3)
    at Object.main (*/assemblyscript/cli/asc.js:590:26)
    at Object.<anonymous> (*/assemblyscript/bin/asc:21:26)
    at Module._compile (internal/modules/cjs/loader.js:688:30)

[MaxGraey]

@DanielRX Great! But instead of AssertionError I guess it should be diagnostic error in ASxxx space similar to "Duplicate decorator" error here

EDIT
Actualy we already have this error. But if you create another one with "Duplicate instance member '{0}' in file '{1}'": 2301 this will be even better

[DanielRX]

Noted, as a side point, we are going to add static and instance errors, so that it covers both cases.

[dcodeIO]

This is emitting a diagnostic with a related range now, indicating both the initial declaration and the duplicate one.