fIx: smaller nits

frontend/src/lib/errorHandling.ts

@@ -0,0 +1,155 @@
+/**
+ * Error handling utilities for consistent error management.
+ * Provides centralized error handling logic across the application.
+ */
+
+/**
+ * Error kind for categorizing errors
+ */
+export type ErrorKind = 
+  | 'render'
+  | 'network'
+  | 'validation'
+  | 'authentication'
+  | 'authorization'
+  | 'notFound'
+  | 'server'
+  | 'unknown'
+
+/**
+ * Error object with kind and message
+ */
+export type AppError = {
+  kind: ErrorKind
+  message: string
+  details?: Record<string, unknown>
+  timestamp: number
+}
+
+/**
+ * Create an error object with consistent structure
+ */
+export function createAppError(
+  kind: ErrorKind,
+  message: string,
+  details?: Record<string, unknown>
+): AppError {
+  return {
+    kind,
+    message,
+    details,
+    timestamp: Date.now(),
+  }
+}
+
+/**
+ * Extract error message from unknown error
+ */
+export function getErrorMessage(error: unknown): string {
+  if (error instanceof Error) {
+    return error.message
+  }
+  if (typeof error === 'string') {
+    return error
+  }
+  if (typeof error === 'object' && error !== null && 'message' in error) {
+    return String(error.message)
+  }
+  return 'An unknown error occurred'
+}
+
+/**
+ * Extract error kind from error
+ */
+export function getErrorKind(error: unknown): ErrorKind {
+  if (error instanceof Error) {
+    const message = error.message.toLowerCase()
+    if (message.includes('network')) return 'network'
+    if (message.includes('validation') || message.includes('invalid')) return 'validation'
+    if (message.includes('auth')) return 'authentication'
+    if (message.includes('forbidden') || message.includes('unauthorized')) return 'authorization'
+    if (message.includes('not found') || message.includes('404')) return 'notFound'
+    if (message.includes('server') || message.includes('500')) return 'server'
+  }
+  return 'unknown'
+}
+
+/**
+ * Format error for display
+ */
+export function formatError(error: AppError | Error | string): string {
+  if (typeof error === 'string') {
+    return error
+  }
+  if (error instanceof Error) {
+    return error.message
+  }
+  return error.message
+}
+
+/**
+ * Check if error is recoverable
+ */
+export function isRecoverableError(error: AppError | Error | string): boolean {
+  if (typeof error === 'string') return false
+  if (error instanceof Error) {
+    const message = error.message.toLowerCase()
+    return ['network', 'timeout', 'connection'].some((term) => message.includes(term))
+  }
+  // error is AppError at this point
+  return ['network', 'server'].includes((error as AppError).kind)
+}
+
+/**
+ * Update error state consistently
+ */
+export function updateErrorState<T extends { error?: unknown }>(
+  state: T,
+  setError: (error: null | { kind: string; message: string }) => void,
+  error: unknown
+): void {
+  setError({
+    kind: 'render',
+    message: getErrorMessage(error),
+  })
+}
+
+/**
+ * Clear error state
+ */
+export function clearErrorState<T extends { error?: unknown }>(
+  state: T,
+  setError: (error: null) => void
+): void {
+  setError(null)
+}
+
+/**
+ * Handle error with consistent logging
+ */
+export function handleError(
+  error: unknown,
+  context?: Record<string, unknown>
+): AppError {
+  const appError = createAppError(
+    getErrorKind(error),
+    getErrorMessage(error),
+    context
+  )
+  
+  console.error('[Error]', appError, context)
+  return appError
+}
+
+/**
+ * Create error handler for async functions
+ */
+export function createErrorHandler<T>(
+  onError?: (error: AppError) => void
+): (error: unknown) => T {
+  return (error: unknown) => {
+    const appError = handleError(error)
+    onError?.(appError)
+    throw error
+  }
+}