src/vs/workbench/contrib/terminal/browser/terminalInstance.ts/TerminalInstance/_parseFixedDimension
class TerminalInstance:	private _parseFixedDimension(value: string): number | undefined {
		if (value === '') {
			return undefined;
		}
		const parsed = parseInt(value);
		if (parsed <= 0) {
			throw new Error(`Could not parse dimension "${value}"`);
		}
		return parsed;
	}