chore: fix auth error message (#1024)

Co-authored-by: Willow (GHOST) <[e-mail]>

app/error.vue

···
 const statusText = computed(() => {
   if (props.error.statusMessage) return props.error.statusMessage
   switch (status.value) {
+    case 401:
+      return 'Unauthorized'
     case 404:
       return 'Page not found'
     case 500:

server/api/auth/atproto.get.ts

···
 
       return handleApiError(error, {
         statusCode: 401,
+        statusMessage: 'Unauthorized',
         message: `${message}. Please login and try again.`,
       })
     }

server/utils/error-handler.ts

···
  * Handles H3 errors, Valibot, and fallbacks in that order
  */
 export function handleApiError(error: unknown, fallback: ErrorOptions): never {
-  // If already a known Nuxt/H3 Error, re-throw
+  // If already a known Nuxt/H3 Error, apply fallback only when the error has a generic 500 status
   if (isError(error)) {
+    if (error.statusCode === 500 && fallback.statusCode) {
+      error.statusCode = fallback.statusCode
+    }
+    if (error.statusMessage === 'Server Error' && fallback.statusMessage) {
+      error.statusMessage = fallback.statusMessage
+    }
     throw error
   }
 
···
   // Generic fallback
   throw createError({
     statusCode: fallback.statusCode ?? 502,
+    statusMessage: fallback.statusMessage,
     message: fallback.message,
   })
 }

shared/types/error.ts

···
 export interface ErrorOptions {
   message: string
   statusCode?: number
+  statusMessage?: string
 }