Referencing a function prototype with no type parameters leads to assertion failure

[DuncanUszkay1]

If you reference a function prototype that requires a type parameter and omit that type parameter, you get an assertion failure rather than a helpful error:

function doit<T,X,O,N>(x: T): T {
  return x
}
export function test(x: i32): void {
  let x = doit;
}

Returns

ERROR: AssertionError: assertion failed
    at assert (/Users/duncanuszkay/src/github.com/Shopify/as-fork/assemblyscript/std/portable/index.js:184:9)
    at Resolver.resolveFunction (/Users/duncanuszkay/src/github.com/Shopify/as-fork/assemblyscript/src/resolver.ts:2691:7)
    at Compiler.compileIdentifierExpression (/Users/duncanuszkay/src/github.com/Shopify/as-fork/assemblyscript/src/compiler.ts:7954:46)
    at Compiler.compileExpression (/Users/duncanuszkay/src/github.com/Shopify/as-fork/assemblyscript/src/compiler.ts:3327:21)
    at Compiler.compileBinaryExpression (/Users/duncanuszkay/src/github.com/Shopify/as-fork/assemblyscript/src/compiler.ts:3735:25)
    at Compiler.compileExpression (/Users/duncanuszkay/src/github.com/Shopify/as-fork/assemblyscript/src/compiler.ts:3302:21)
    at Compiler.compileVariableStatement (/Users/duncanuszkay/src/github.com/Shopify/as-fork/assemblyscript/src/compiler.ts:2868:25)
    at Compiler.compileStatement (/Users/duncanuszkay/src/github.com/Shopify/as-fork/assemblyscript/src/compiler.ts:1984:21)
    at Compiler.compileStatements (/Users/duncanuszkay/src/github.com/Shopify/as-fork/assemblyscript/src/compiler.ts:2031:23)
    at Compiler.compileFunctionBody (/Users/duncanuszkay/src/github.com/Shopify/as-fork/assemblyscript/src/compiler.ts:1393:20)

This came up for us when we made this typo:

let x = doit<String("hey!"); //Forgot the other >

Going to open up a PR to fix this momentarily