src/vs/workbench/contrib/terminal/browser/terminalService.ts/TerminalService/getInstanceFromId
class TerminalService:	getInstanceFromId(terminalId: number): ITerminalInstance | undefined {
		let bgIndex = -1;
		this._backgroundedTerminalInstances.forEach((terminalInstance, i) => {
			if (terminalInstance.instanceId === terminalId) {
				bgIndex = i;
			}
		});
		if (bgIndex !== -1) {
			return this._backgroundedTerminalInstances[bgIndex];
		}
		try {
			return this.instances[this._getIndexFromId(terminalId)];
		} catch {
			return undefined;
		}
	}