resolveJsonModule transpile does not strip trailing commas

[cspotcode]

TypeScript Version: 2.9.1

Search Terms:

JSON
resolveJsonModule
json trailing comma

Code

import * as ts from 'typescript';
console.log(ts.version);
const output = ts.transpileModule(
    `
        {"foo": 123,} // note trailing comma
    `,
    {
        fileName: 'foo.json',
        compilerOptions: {
            resolveJsonModule: true,
            removeComments: true
        },
        reportDiagnostics: true
    }
);
console.dir(output.diagnostics); // no errors
console.dir(output.outputText); // '{ "foo": 123, }\r\n' still has trailing comma

Expected behavior:

Emitted JSON does not have trailing comma: { "foo": 123 }
...or compiler emits a diagnostic to tell me the trailing comma is not allowed in input json.

Actual behavior:

Emitted JSON has trailing comma: { "foo": 123, } and no diagnostics are reported.

Playground Link:

N/A because Playground assumes .ts file extension.

Related Issues:

[mhegazy]

@sheetalkamat can you take a look please.