/**
 * The general runtime assertion utilities of `@xmachines/play`.
 *
 * @packageDocumentation
 */
/**
 * Asserts that `value` is not `null` and not `undefined`, then returns it with the
 * type `NonNullable<V>`. One expression therefore holds the guard and the narrowed
 * value.
 *
 * A non-null assertion (`value!`) is different: it produces `undefined`, and your
 * code then fails later with a message such as "undefined is not an object". This
 * function throws a clear error at the point of the failure.
 *
 * An assertion function of the form `asserts value is T` is also different: this
 * function returns the narrowed value directly. Therefore the call site needs no
 * second variable and no `as` cast.
 *
 * @param value - The value to check.
 * @param name  - The optional name in the error message. It identifies the missing
 *   value, for example the name of the variable or of the injection key.
 * @returns `value` with the type `NonNullable<V>`, without `null` and without `undefined`.
 * @throws {NonNullableError} When `value` is `null` or `undefined`.
 *
 * @example
 * ```ts
 * import { assertNonNullable } from "@xmachines/play";
 *
 * // inject() and assertNonNullable in one line, with no `!` and no second variable:
 * const actor = assertNonNullable(inject<AuthActor>("actor"), "actor");
 *
 * // A lookup of an element:
 * const el = assertNonNullable(document.getElementById("app"), "#app");
 * ```
 */
export declare function assertNonNullable<V>(value: V, name?: string): NonNullable<V>;
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