_compileVM() {
		let script = this._compiledVM;
		if (!script) {
			this._compiledVM = script = this._compile('', '');
		}
		return script;
	}
Will return the cached version of the script intended for VM or compile it.

@private
@return {vm.Script} The compiled script
@throws {SyntaxError} If there is a syntax error in the script.