TS language syntax highlighting issue in `new <object>[<key>]()` pattern

[pushkine]

vscode 1.51.1
ts 4.0.5 & 4.2.0-dev.20201123

declare const key: string;
declare const value: string;
declare const Classes: { [key: string]: any };
const k = value.slice(0, value.indexOf("<"));
new Classes[value.slice(0, value.indexOf("<"))]();