routie dev init since i didn't adhere to any proper guidance up until now

frontend/node_modules/rxjs/src/internal/Notification.ts

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+import { PartialObserver, ObservableNotification, CompleteNotification, NextNotification, ErrorNotification } from './types';
+import { Observable } from './Observable';
+import { EMPTY } from './observable/empty';
+import { of } from './observable/of';
+import { throwError } from './observable/throwError';
+import { isFunction } from './util/isFunction';
+
+// TODO: When this enum is removed, replace it with a type alias. See #4556.
+/**
+ * @deprecated Use a string literal instead. `NotificationKind` will be replaced with a type alias in v8.
+ * It will not be replaced with a const enum as those are not compatible with isolated modules.
+ */
+export enum NotificationKind {
+  NEXT = 'N',
+  ERROR = 'E',
+  COMPLETE = 'C',
+}
+
+/**
+ * Represents a push-based event or value that an {@link Observable} can emit.
+ * This class is particularly useful for operators that manage notifications,
+ * like {@link materialize}, {@link dematerialize}, {@link observeOn}, and
+ * others. Besides wrapping the actual delivered value, it also annotates it
+ * with metadata of, for instance, what type of push message it is (`next`,
+ * `error`, or `complete`).
+ *
+ * @see {@link materialize}
+ * @see {@link dematerialize}
+ * @see {@link observeOn}
+ * @deprecated It is NOT recommended to create instances of `Notification` directly.
+ * Rather, try to create POJOs matching the signature outlined in {@link ObservableNotification}.
+ * For example: `{ kind: 'N', value: 1 }`, `{ kind: 'E', error: new Error('bad') }`, or `{ kind: 'C' }`.
+ * Will be removed in v8.
+ */
+export class Notification<T> {
+  /**
+   * A value signifying that the notification will "next" if observed. In truth,
+   * This is really synonymous with just checking `kind === "N"`.
+   * @deprecated Will be removed in v8. Instead, just check to see if the value of `kind` is `"N"`.
+   */
+  readonly hasValue: boolean;
+
+  /**
+   * Creates a "Next" notification object.
+   * @param kind Always `'N'`
+   * @param value The value to notify with if observed.
+   * @deprecated Internal implementation detail. Use {@link Notification#createNext createNext} instead.
+   */
+  constructor(kind: 'N', value?: T);
+  /**
+   * Creates an "Error" notification object.
+   * @param kind Always `'E'`
+   * @param value Always `undefined`
+   * @param error The error to notify with if observed.
+   * @deprecated Internal implementation detail. Use {@link Notification#createError createError} instead.
+   */
+  constructor(kind: 'E', value: undefined, error: any);
+  /**
+   * Creates a "completion" notification object.
+   * @param kind Always `'C'`
+   * @deprecated Internal implementation detail. Use {@link Notification#createComplete createComplete} instead.
+   */
+  constructor(kind: 'C');
+  constructor(public readonly kind: 'N' | 'E' | 'C', public readonly value?: T, public readonly error?: any) {
+    this.hasValue = kind === 'N';
+  }
+
+  /**
+   * Executes the appropriate handler on a passed `observer` given the `kind` of notification.
+   * If the handler is missing it will do nothing. Even if the notification is an error, if
+   * there is no error handler on the observer, an error will not be thrown, it will noop.
+   * @param observer The observer to notify.
+   */
+  observe(observer: PartialObserver<T>): void {
+    return observeNotification(this as ObservableNotification<T>, observer);
+  }
+
+  /**
+   * Executes a notification on the appropriate handler from a list provided.
+   * If a handler is missing for the kind of notification, nothing is called
+   * and no error is thrown, it will be a noop.
+   * @param next A next handler
+   * @param error An error handler
+   * @param complete A complete handler
+   * @deprecated Replaced with {@link Notification#observe observe}. Will be removed in v8.
+   */
+  do(next: (value: T) => void, error: (err: any) => void, complete: () => void): void;
+  /**
+   * Executes a notification on the appropriate handler from a list provided.
+   * If a handler is missing for the kind of notification, nothing is called
+   * and no error is thrown, it will be a noop.
+   * @param next A next handler
+   * @param error An error handler
+   * @deprecated Replaced with {@link Notification#observe observe}. Will be removed in v8.
+   */
+  do(next: (value: T) => void, error: (err: any) => void): void;
+  /**
+   * Executes the next handler if the Notification is of `kind` `"N"`. Otherwise
+   * this will not error, and it will be a noop.
+   * @param next The next handler
+   * @deprecated Replaced with {@link Notification#observe observe}. Will be removed in v8.
+   */
+  do(next: (value: T) => void): void;
+  do(nextHandler: (value: T) => void, errorHandler?: (err: any) => void, completeHandler?: () => void): void {
+    const { kind, value, error } = this;
+    return kind === 'N' ? nextHandler?.(value!) : kind === 'E' ? errorHandler?.(error) : completeHandler?.();
+  }
+
+  /**
+   * Executes a notification on the appropriate handler from a list provided.
+   * If a handler is missing for the kind of notification, nothing is called
+   * and no error is thrown, it will be a noop.
+   * @param next A next handler
+   * @param error An error handler
+   * @param complete A complete handler
+   * @deprecated Replaced with {@link Notification#observe observe}. Will be removed in v8.
+   */
+  accept(next: (value: T) => void, error: (err: any) => void, complete: () => void): void;
+  /**
+   * Executes a notification on the appropriate handler from a list provided.
+   * If a handler is missing for the kind of notification, nothing is called
+   * and no error is thrown, it will be a noop.
+   * @param next A next handler
+   * @param error An error handler
+   * @deprecated Replaced with {@link Notification#observe observe}. Will be removed in v8.
+   */
+  accept(next: (value: T) => void, error: (err: any) => void): void;
+  /**
+   * Executes the next handler if the Notification is of `kind` `"N"`. Otherwise
+   * this will not error, and it will be a noop.
+   * @param next The next handler
+   * @deprecated Replaced with {@link Notification#observe observe}. Will be removed in v8.
+   */
+  accept(next: (value: T) => void): void;
+
+  /**
+   * Executes the appropriate handler on a passed `observer` given the `kind` of notification.
+   * If the handler is missing it will do nothing. Even if the notification is an error, if
+   * there is no error handler on the observer, an error will not be thrown, it will noop.
+   * @param observer The observer to notify.
+   * @deprecated Replaced with {@link Notification#observe observe}. Will be removed in v8.
+   */
+  accept(observer: PartialObserver<T>): void;
+  accept(nextOrObserver: PartialObserver<T> | ((value: T) => void), error?: (err: any) => void, complete?: () => void) {
+    return isFunction((nextOrObserver as any)?.next)
+      ? this.observe(nextOrObserver as PartialObserver<T>)
+      : this.do(nextOrObserver as (value: T) => void, error as any, complete as any);
+  }
+
+  /**
+   * Returns a simple Observable that just delivers the notification represented
+   * by this Notification instance.
+   *
+   * @deprecated Will be removed in v8. To convert a `Notification` to an {@link Observable},
+   * use {@link of} and {@link dematerialize}: `of(notification).pipe(dematerialize())`.
+   */
+  toObservable(): Observable<T> {
+    const { kind, value, error } = this;
+    // Select the observable to return by `kind`
+    const result =
+      kind === 'N'
+        ? // Next kind. Return an observable of that value.
+          of(value!)
+        : //
+        kind === 'E'
+        ? // Error kind. Return an observable that emits the error.
+          throwError(() => error)
+        : //
+        kind === 'C'
+        ? // Completion kind. Kind is "C", return an observable that just completes.
+          EMPTY
+        : // Unknown kind, return falsy, so we error below.
+          0;
+    if (!result) {
+      // TODO: consider removing this check. The only way to cause this would be to
+      // use the Notification constructor directly in a way that is not type-safe.
+      // and direct use of the Notification constructor is deprecated.
+      throw new TypeError(`Unexpected notification kind ${kind}`);
+    }
+    return result;
+  }
+
+  private static completeNotification = new Notification('C') as Notification<never> & CompleteNotification;
+  /**
+   * A shortcut to create a Notification instance of the type `next` from a
+   * given value.
+   * @param value The `next` value.
+   * @return The "next" Notification representing the argument.
+   * @deprecated It is NOT recommended to create instances of `Notification` directly.
+   * Rather, try to create POJOs matching the signature outlined in {@link ObservableNotification}.
+   * For example: `{ kind: 'N', value: 1 }`, `{ kind: 'E', error: new Error('bad') }`, or `{ kind: 'C' }`.
+   * Will be removed in v8.
+   */
+  static createNext<T>(value: T) {
+    return new Notification('N', value) as Notification<T> & NextNotification<T>;
+  }
+
+  /**
+   * A shortcut to create a Notification instance of the type `error` from a
+   * given error.
+   * @param err The `error` error.
+   * @return The "error" Notification representing the argument.
+   * @deprecated It is NOT recommended to create instances of `Notification` directly.
+   * Rather, try to create POJOs matching the signature outlined in {@link ObservableNotification}.
+   * For example: `{ kind: 'N', value: 1 }`, `{ kind: 'E', error: new Error('bad') }`, or `{ kind: 'C' }`.
+   * Will be removed in v8.
+   */
+  static createError(err?: any) {
+    return new Notification('E', undefined, err) as Notification<never> & ErrorNotification;
+  }
+
+  /**
+   * A shortcut to create a Notification instance of the type `complete`.
+   * @return The valueless "complete" Notification.
+   * @deprecated It is NOT recommended to create instances of `Notification` directly.
+   * Rather, try to create POJOs matching the signature outlined in {@link ObservableNotification}.
+   * For example: `{ kind: 'N', value: 1 }`, `{ kind: 'E', error: new Error('bad') }`, or `{ kind: 'C' }`.
+   * Will be removed in v8.
+   */
+  static createComplete(): Notification<never> & CompleteNotification {
+    return Notification.completeNotification;
+  }
+}
+
+/**
+ * Executes the appropriate handler on a passed `observer` given the `kind` of notification.
+ * If the handler is missing it will do nothing. Even if the notification is an error, if
+ * there is no error handler on the observer, an error will not be thrown, it will noop.
+ * @param notification The notification object to observe.
+ * @param observer The observer to notify.
+ */
+export function observeNotification<T>(notification: ObservableNotification<T>, observer: PartialObserver<T>) {
+  const { kind, value, error } = notification as any;
+  if (typeof kind !== 'string') {
+    throw new TypeError('Invalid notification, missing "kind"');
+  }
+  kind === 'N' ? observer.next?.(value!) : kind === 'E' ? observer.error?.(error) : observer.complete?.();
+}