import { OperatorFunction } from 'rxjs';
/**
 * Creates an operator function that throws an error if the source Observable emits an empty value.
 *
 * This function is a higher-order function that returns an operator function specifically designed to be used with Observables.
 * When applied to an Observable, the operator function checks each emitted value, and if any value is `null` or `undefined`,
 * it throws an error with the provided message. This ensures that the resulting Observable only emits non-nullable values.
 *
 * @param {string} message - The error message to be thrown if the Observable emits an empty value.
 * @returns {OperatorFunction<T, NonNullable<T>>} An operator function that can be applied to an Observable of type T,
 * resulting in an Observable of type NonNullable<T>.
 *
 * @template T - The type of items emitted by the source Observable.
 *
 * @example
 * // Usage with an RxJS Observable
 * import { of } from 'rxjs';
 * import { throwIfEmpty } from './path/to/this/function';
 *
 * const source$ = of(null);
 * const result$ = source$.pipe(throwIfEmpty('Value cannot be empty'));
 * result$.subscribe({
 * next: value => console.log(value),
 * error: err => console.error(err)
 * });
 */
export declare function throwIfEmpty<T>(message: string): OperatorFunction<T, NonNullable<T>>;