Changes overlap removing unused function and its unused parameter

TypeScript Version: 2.9.0-dev.20180516

Search Terms:

Code

/// <reference path='fourslash.ts' />

////export {};
////function f(x) {}

verify.codeFixAll({
    fixId: "unusedIdentifier_delete",
    fixAllDescription: "Delete all unused declarations",
    newFileContent: "?",
});

Expected behavior:

No debug failure.

Actual behavior:

     Error: Debug Failure. False expression: Changes overlap
Verbose Debug Information: {"pos":11,"end":27} and {"pos":22,"end":23}