feat: better error handling for oidc api key

This also ships with a better error page

app/server/headscale/api/error.ts

@@ -1,123 +1,72 @@
-import { data } from 'react-router';
 import { errors } from 'undici';
 
+/**
+ * Helper function that determines if an error is a Node.js exception
+ * @param - The error to check
+ * @returns True if the error is a Node.js exception, false otherwise
+ */
 function isNodeNetworkError(error: unknown): error is NodeJS.ErrnoException {
-	if (typeof error !== 'object' || error === null) {
-		return false;
-	}
-
-	const keys = Object.keys(error as Record<string, unknown>);
-	return keys.includes('code') && keys.includes('errno');
+	return (
+		error != null &&
+		typeof error === 'object' &&
+		'code' in error &&
+		'errno' in error
+	);
 }
 
-export function friendlyError(givenError: unknown) {
-	let error: unknown = givenError;
+/**
+ * A friendly error representation for Headscale connection issues.
+ */
+export interface HeadscaleConnectionError {
+	requestUrl: string;
+	errorCode: string;
+	errorMessage: string;
+	extraData: Record<string, unknown> | null;
+}
+
+/**
+ * Convert an Undici error into a friendly HeadscaleAPIError.
+ * This is used to avoid exposing rough error edges to the user.
+ *
+ * @param error - The Undici error to convert.
+ * @param requestUrl - The URL of the request that caused the error.
+ * @returns A friendly HeadscaleAPIError.
+ */
+export function undiciToFriendlyError(
+	error: unknown,
+	requestUrl: string,
+): HeadscaleConnectionError {
+	// MARK: Do we need to go deeper into causes here?
 	if (error instanceof AggregateError) {
 		error = error.errors[0];
 	}
 
-	switch (true) {
-		case error instanceof errors.BodyTimeoutError:
-		case error instanceof errors.ConnectTimeoutError:
-		case error instanceof errors.HeadersTimeoutError:
-			return data('Timed out waiting for a response from the Headscale API', {
-				statusText: 'Request Timeout',
-				status: 408,
-			});
-
-		case error instanceof errors.SocketError:
-		case error instanceof errors.SecureProxyConnectionError:
-		case error instanceof errors.ClientClosedError:
-		case error instanceof errors.ClientDestroyedError:
-		case error instanceof errors.RequestAbortedError:
-			return data('The Headscale API is not reachable', {
-				statusText: 'Service Unavailable',
-				status: 503,
-			});
-
-		case error instanceof errors.InvalidArgumentError:
-		case error instanceof errors.InvalidReturnValueError:
-		case error instanceof errors.NotSupportedError:
-			return data('Unable to make a request (this is most likely a bug)', {
-				statusText: 'Internal Server Error',
-				status: 500,
-			});
-
-		case error instanceof errors.HeadersOverflowError:
-		case error instanceof errors.RequestContentLengthMismatchError:
-		case error instanceof errors.ResponseContentLengthMismatchError:
-		case error instanceof errors.ResponseExceededMaxSizeError:
-			return data('The Headscale API returned a malformed response', {
-				statusText: 'Bad Gateway',
-				status: 502,
-			});
-
-		case isNodeNetworkError(error):
-			if (error.code === 'ECONNREFUSED') {
-				return data('The Headscale API is not reachable', {
-					statusText: 'Service Unavailable',
-					status: 503,
-				});
-			}
-
-			if (error.code === 'ENOTFOUND') {
-				return data('The Headscale API is not reachable', {
-					statusText: 'Service Unavailable',
-					status: 503,
-				});
-			}
-
-			if (error.code === 'EAI_AGAIN') {
-				return data('The Headscale API is not reachable', {
-					statusText: 'Service Unavailable',
-					status: 503,
-				});
-			}
-
-			if (error.code === 'ETIMEDOUT') {
-				return data('Timed out waiting for a response from the Headscale API', {
-					statusText: 'Request Timeout',
-					status: 408,
-				});
-			}
-
-			if (error.code === 'ECONNRESET') {
-				return data('The Headscale API is not reachable', {
-					statusText: 'Service Unavailable',
-					status: 503,
-				});
-			}
-
-			if (error.code === 'EPIPE') {
-				return data('The Headscale API is not reachable', {
-					statusText: 'Service Unavailable',
-					status: 503,
-				});
-			}
-
-			if (error.code === 'ENETUNREACH') {
-				return data('The Headscale API is not reachable', {
-					statusText: 'Service Unavailable',
-					status: 503,
-				});
-			}
-
-			if (error.code === 'ENETRESET') {
-				return data('The Headscale API is not reachable', {
-					statusText: 'Service Unavailable',
-					status: 503,
-				});
-			}
-
-			return data('The Headscale API is not reachable', {
-				statusText: 'Service Unavailable',
-				status: 503,
-			});
-
-		default:
-			return data((error as Error).message ?? 'An unknown error occurred', {
-				statusText: 'Internal Server Error',
-				status: 500,
-			});
+	if (error instanceof errors.UndiciError) {
+		return {
+			requestUrl,
+			errorCode: error.code,
+			errorMessage: error.message,
+			extraData: null,
+		};
 	}
+
+	if (isNodeNetworkError(error)) {
+		return {
+			requestUrl,
+			errorCode: error.code ?? 'UNKNOWN_NODE_NETWORK_ERROR',
+			errorMessage: error.message,
+			extraData: {
+				syscall: error.syscall,
+				path: error.path,
+				errno: error.errno,
+			},
+		};
+	}
+
+	return {
+		requestUrl,
+		errorCode: 'UNKNOWN_ERROR',
+		errorMessage: 'An unknown error occured',
+		extraData: null,
+	};
 }