space-before-function-paren: Cannot read property 'end' of undefined

[clebert]

Bug Report

• TSLint version: 5.3.2
• TypeScript version: 2.3.3
• Running TSLint via: CLI

TypeScript code being linted

export type Fn = (foo: string) => Promise<string>;

export const noWarning: Fn = async (foo) => foo;

export const warning: Fn = async foo => foo;

with tslint.json configuration:

{
  "rules": {
    "space-before-function-paren": [true, {
      "asyncArrow": "always"
    }]
  }
}

Actual behavior

Warning: Cannot read property 'end' of undefined

Expected behavior

No warning (with TSLint 5.2.0 there is no problem)

[adidahiya]

fixed by #2833