fix: Add error handling to Settings form

This commit adds error handling to the settings form in the Settings.vue page. A new 'errors' object has been introduced to capture and display errors returned from the API. The onSubmit event also has been modified for handling a try/catch block for potential API errors.
The associated unit test was updated to ensure proper behavior when an API error is returned.
This improvement aims to provide a better user experience by clearly communicating issues with the user's changes.

close #58

src/pages/Settings.spec.ts

@@ -1,3 +1,4 @@
+import userEvent from '@testing-library/user-event'
 import { fireEvent, render, waitFor } from '@testing-library/vue'
 import { describe, expect, it, vi } from 'vitest'
 import { router } from 'src/router.ts'
@@ -80,4 +81,16 @@ describe('# Settings Page', () => {
       }
     `)
   })
+
+  it('should display error message when api returned some errors', async () => {
+    server.use(['PUT', '/api/user', 400, { errors: { username: ['has already been taken'] } }])
+    const { getByRole, getByPlaceholderText, getByText } = render(Settings, renderOptions({
+      initialState: { user: { user: fixtures.user } },
+    }))
+
+    await userEvent.type(getByPlaceholderText('Your name'), 'new username')
+    await userEvent.click(getByRole('button', { name: 'Update Settings' }))
+
+    expect(getByText('username has already been taken')).toBeInTheDocument()
+  })
 })

src/pages/Settings.vue

@@ -7,6 +7,12 @@
             Your Settings
           </h1>
 
+          <ul class="error-messages">
+            <li v-for="(error, field) in errors" :key="field">
+              {{ field }} {{ error ? error[0] : '' }}
+            </li>
+          </ul>
+
           <form @submit.prevent="onSubmit">
             <fieldset>
               <fieldset class="form-group">
@@ -75,22 +81,31 @@
 </template>
 
 <script setup lang="ts">
-import { computed, onMounted, reactive } from 'vue'
+import { computed, onMounted, reactive, ref } from 'vue'
 import { routerPush } from 'src/router'
-import { api } from 'src/services'
+import { api, isFetchError } from 'src/services'
 import type { UpdateUser } from 'src/services/api'
 import { useUserStore } from 'src/store/user'
 
 const form: UpdateUser = reactive({})
 
 const userStore = useUserStore()
+const errors = ref()
 
 const onSubmit = async () => {
+  errors.value = {}
+
+  try {
     // eslint-disable-next-line unicorn/no-array-reduce
     const filteredForm = Object.entries(form).reduce((form, [k, v]) => v === null ? form : Object.assign(form, { [k]: v }), {})
     const userData = await api.user.updateCurrentUser({ user: filteredForm }).then(res => res.data.user)
     userStore.updateUser(userData)
     await routerPush('profile', { username: userData.username })
+  } catch (error) {
+    if (isFetchError(error)) {
+      errors.value = error.error?.errors
+    }
+  }
 }
 
 const onLogout = async () => {