src/vs/editor/contrib/quickAccess/gotoLineQuickAccess.ts/AbstractGotoLineQuickAccessProvider/isValidLineNumber
class AbstractGotoLineQuickAccessProvider:	private isValidLineNumber(editor: IEditor, lineNumber: number | undefined): boolean {
		if (!lineNumber || typeof lineNumber !== 'number') {
			return false;
		}

		return lineNumber > 0 && lineNumber <= this.lineCount(editor);
	}