Silent warning when argv.json has syntax errors

[joaomoreno]

From #212664

It seems that if the argv.json file has a syntax error (ie trailing comma), then we silently ignore all properties within. This is the reason why crash reporting wasn't enabled for me in #212664. My full file was:

// This configuration file allows you to pass permanent command line arguments to VS Code.
// Only a subset of arguments is currently supported to reduce the likelihood of breaking
// the installation.
//
// PLEASE DO NOT CHANGE WITHOUT UNDERSTANDING THE IMPACT
//
// NOTE: Changing this file requires a restart of VS Code.
{
	// Use software rendering instead of hardware accelerated rendering.
	// This can help in cases where you see rendering issues in VS Code.
	// "disable-hardware-acceleration": true,
	// Allows to disable crash reporting.
	// Should restart the app if the value is changed.
	"enable-crash-reporter": true,
	// Unique id used for correlating crash reports sent from this instance.
	// Do not edit this value.
	"crash-reporter-id": "2f300b31-7453-4506-97d0-93411b2c21c7",
	"locale": "en",
	// "log-level": "trace"
}

Notice the trailing comma after locale.

A few ideas:

• We should further sanitize the JSON such that trailing commas are removed before passing it to JSON.parse.
• We should also show a warning notification on startup so the user is aware of the issue, with an action to open the file.