import { HttpErrorResponse } from '@angular/common/http';
export declare function extractErrorType(reason: HttpErrorResponse): string;
export declare function unsupportedOperation(...vars: any[]): Error;
export declare function requireNonNull(var1: any, varName?: string): void;
export declare function requireNonEmptyArray(arr: any[], arrName?: string): void;
export declare function tryOrLog<T>(f: () => T): T;