Use jsonc-parser instead of LKG compiler in build

Profiling the build roughly half of the time spent loading the
build is spent importing typescript.js, for this one function.

Since this stack is already adding required devDependencies, switch
readJson to use jsonc-parser (published by the VS Code team), rather
than importing the entire LKG typescript.js library.

Author: jakebailey

package-lock.json

@@ -83,6 +83,7 @@
         "gulp-newer": "latest",
         "gulp-rename": "latest",
         "gulp-sourcemaps": "latest",
+        "jsonc-parser": "^3.2.0",
         "merge2": "latest",
         "minimist": "latest",
         "mkdirp": "latest",

package.json

@@ -7,12 +7,12 @@ import path from "path";
 import log from "fancy-log";
 import del from "del";
 import File from "vinyl";
-import ts from "../../lib/typescript.js";
 import chalk from "chalk";
 import which from "which";
 import { spawn } from "child_process";
 import { Duplex } from "stream";
 import assert from "assert";
+import JSONC from "jsonc-parser";
 
 /**
  * Executes the provided command once with the supplied arguments.
@@ -53,47 +53,12 @@ export async function exec(cmd, args, options = {}) {
 }
 
 /**
- * @param {ts.Diagnostic[]} diagnostics
- * @param {{ cwd?: string, pretty?: boolean }} [options]
- */
-function formatDiagnostics(diagnostics, options) {
-    return options && options.pretty
-        ? ts.formatDiagnosticsWithColorAndContext(diagnostics, getFormatDiagnosticsHost(options && options.cwd))
-        : ts.formatDiagnostics(diagnostics, getFormatDiagnosticsHost(options && options.cwd));
-}
-
-/**
- * @param {ts.Diagnostic[]} diagnostics
- * @param {{ cwd?: string }} [options]
- */
-function reportDiagnostics(diagnostics, options) {
-    log(formatDiagnostics(diagnostics, { cwd: options && options.cwd, pretty: process.stdout.isTTY }));
-}
-
-/**
- * @param {string | undefined} cwd
- * @returns {ts.FormatDiagnosticsHost}
- */
-function getFormatDiagnosticsHost(cwd) {
-    return {
-        getCanonicalFileName: fileName => fileName,
-        getCurrentDirectory: () => cwd ?? process.cwd(),
-        getNewLine: () => ts.sys.newLine,
-    };
-}
-
-/**
- * Reads JSON data with optional comments using the LKG TypeScript compiler
+ * Reads JSON data with optional comments.
  * @param {string} jsonPath
  */
 export function readJson(jsonPath) {
     const jsonText = fs.readFileSync(jsonPath, "utf8");
-    const result = ts.parseConfigFileTextToJson(jsonPath, jsonText);
-    if (result.error) {
-        reportDiagnostics([result.error]);
-        throw new Error("An error occurred during parse.");
-    }
-    return result.config;
+    return JSONC.parse(jsonText);
 }
 
 /**