Robust Angular Error Handling and Recovery

This challenge focuses on implementing robust error handling and recovery mechanisms within an Angular application. You will create a system that gracefully catches, logs, and recovers from unexpected errors, ensuring a better user experience and application stability. This is crucial for any production-ready application where unhandled errors can lead to crashes and user frustration.

Problem Description

Your task is to build a comprehensive error handling strategy in an Angular application. This involves implementing a global error handler, creating a mechanism to display user-friendly error messages, and optionally, implementing a way to recover from certain types of errors without a full page reload.

What needs to be achieved:

Global Error Handling: Implement a custom Angular Error Handler that intercepts all uncaught errors.
Error Logging: Log all intercepted errors to the console (simulating a more robust logging service).
User-Friendly Feedback: Display a non-intrusive, user-friendly message to the user when an error occurs.
Error Recovery (Optional but Recommended): Implement a basic recovery mechanism for specific error types (e.g., a network error that can be retried).

Key requirements:

Create a service responsible for handling and processing errors.
Register this service as the application's global error handler.
When an error occurs, the application should not crash.
The user should be informed about the error in a polite way.
Consider how to differentiate between critical errors that require a full page refresh (or re-initialization) and recoverable errors.

Expected behavior:

When a component or service throws an uncaught error, the global error handler should catch it.
The error details (message, stack trace) should be logged.
A visible, user-friendly message should appear on the screen (e.g., a toast notification, a banner, or a modal).
For recoverable errors, there should be an option for the user to attempt an action that might fix the issue (e.g., a "Retry" button).

Important edge cases to consider:

Errors occurring during component initialization.
Errors occurring during asynchronous operations (e.g., HTTP requests, promises).
Errors occurring within the error handling mechanism itself (e.g., if the logging service fails).
Handling errors that may not have a clear "recovery" path.

Examples

Example 1: Uncaught Component Error

Scenario: A component has a button that, when clicked, intentionally throws an error.

Input:

User clicks the "Throw Error" button in a component.

The component code:

throw new Error('Something went wrong in the component!');

Output:

The application console logs the error: Error: Something went wrong in the component! with stack trace.
A toast notification appears saying: "An unexpected error occurred. Please try again later."
The application remains functional, and other parts of the UI are interactive.

Explanation: The global error handler catches the Error thrown by the component, logs it, and displays a user-friendly message. The application doesn't crash.

Example 2: Recoverable HTTP Error

Scenario: A service attempts to fetch data from an API that is temporarily unavailable (e.g., 503 Service Unavailable).

Input:

A service method calls an API endpoint that returns a 503 error.
The error handler identifies this as a "network" or "service unavailable" type of error.

Output:

The application console logs the HTTP error.
A toast notification appears saying: "The server is currently unavailable. Would you like to try again?" with "Retry" and "Dismiss" buttons.
If the user clicks "Retry", the service method is called again.
If the user clicks "Dismiss", the error message is dismissed, and the UI might display a placeholder or a message indicating data is unavailable.

Explanation: The error handler recognizes the specific error type, informs the user, and provides a recovery option.

Constraints

The solution must be implemented in TypeScript.
The solution must use Angular's built-in error handling mechanisms or standard Angular practices.
Avoid using window.onerror directly for primary error handling; leverage Angular's ErrorHandler interface.
The error logging should be performed to the browser's console (console.error).
For the recovery mechanism, simulate retry logic for a specific error type (e.g., by checking error.status for an HTTP error).
The UI feedback mechanism can be a simple alert or a basic console log indicating a message is being displayed (for simplicity, a full UI toast component implementation is not strictly required for this challenge, but understanding how it would work is key).

Notes

Consider using Angular's HttpClient and its HttpErrorResponse to simulate network errors.
Think about how you would categorize errors to decide if recovery is possible.
The goal is to demonstrate a structured approach to error management, not necessarily a complex UI for error reporting.
You might want to create a custom ErrorStateMatcher or similar concept to identify recoverable errors.
For the purpose of this challenge, you can simulate errors by throwing them manually or by configuring your Angular HttpClient to return errors.

Robust Angular Error Handling and Recovery

Problem Description

What needs to be achieved:

Global Error Handling: Implement a custom Angular Error Handler that intercepts all uncaught errors.
Error Logging: Log all intercepted errors to the console (simulating a more robust logging service).
User-Friendly Feedback: Display a non-intrusive, user-friendly message to the user when an error occurs.
Error Recovery (Optional but Recommended): Implement a basic recovery mechanism for specific error types (e.g., a network error that can be retried).

Key requirements:

Create a service responsible for handling and processing errors.
Register this service as the application's global error handler.
When an error occurs, the application should not crash.
The user should be informed about the error in a polite way.
Consider how to differentiate between critical errors that require a full page refresh (or re-initialization) and recoverable errors.

Expected behavior:

When a component or service throws an uncaught error, the global error handler should catch it.
The error details (message, stack trace) should be logged.
A visible, user-friendly message should appear on the screen (e.g., a toast notification, a banner, or a modal).
For recoverable errors, there should be an option for the user to attempt an action that might fix the issue (e.g., a "Retry" button).

Important edge cases to consider:

Errors occurring during component initialization.
Errors occurring during asynchronous operations (e.g., HTTP requests, promises).
Errors occurring within the error handling mechanism itself (e.g., if the logging service fails).
Handling errors that may not have a clear "recovery" path.

Examples

Example 1: Uncaught Component Error

Scenario: A component has a button that, when clicked, intentionally throws an error.

Input:

User clicks the "Throw Error" button in a component.

The component code:

throw new Error('Something went wrong in the component!');

Output:

The application console logs the error: Error: Something went wrong in the component! with stack trace.
A toast notification appears saying: "An unexpected error occurred. Please try again later."
The application remains functional, and other parts of the UI are interactive.

Explanation: The global error handler catches the Error thrown by the component, logs it, and displays a user-friendly message. The application doesn't crash.

Example 2: Recoverable HTTP Error

Scenario: A service attempts to fetch data from an API that is temporarily unavailable (e.g., 503 Service Unavailable).

Input:

A service method calls an API endpoint that returns a 503 error.
The error handler identifies this as a "network" or "service unavailable" type of error.

Output:

The application console logs the HTTP error.
A toast notification appears saying: "The server is currently unavailable. Would you like to try again?" with "Retry" and "Dismiss" buttons.
If the user clicks "Retry", the service method is called again.
If the user clicks "Dismiss", the error message is dismissed, and the UI might display a placeholder or a message indicating data is unavailable.

Explanation: The error handler recognizes the specific error type, informs the user, and provides a recovery option.

Constraints

The solution must be implemented in TypeScript.
The solution must use Angular's built-in error handling mechanisms or standard Angular practices.
Avoid using window.onerror directly for primary error handling; leverage Angular's ErrorHandler interface.
The error logging should be performed to the browser's console (console.error).
For the recovery mechanism, simulate retry logic for a specific error type (e.g., by checking error.status for an HTTP error).
The UI feedback mechanism can be a simple alert or a basic console log indicating a message is being displayed (for simplicity, a full UI toast component implementation is not strictly required for this challenge, but understanding how it would work is key).

Notes

Consider using Angular's HttpClient and its HttpErrorResponse to simulate network errors.
Think about how you would categorize errors to decide if recovery is possible.
The goal is to demonstrate a structured approach to error management, not necessarily a complex UI for error reporting.
You might want to create a custom ErrorStateMatcher or similar concept to identify recoverable errors.
For the purpose of this challenge, you can simulate errors by throwing them manually or by configuring your Angular HttpClient to return errors.