fix: Properly handle login errors

src/routes/login/+page.server.ts

@@ -5,6 +5,7 @@ import { redirect } from '@sveltejs/kit';
 import { fail, message, setError, superValidate } from 'sveltekit-superforms';
 import { zod } from 'sveltekit-superforms/adapters';
 import type { Actions } from './$types';
+import type { APIError } from 'better-auth/api';
 
 export async function load({ request }) {
   const session = await auth.api.getSession({
@@ -25,35 +26,41 @@ export const actions = {
     const email = form.data.email;
     const password = form.data.password;
 
-    if (!form.valid) {
-      return fail(400, { form });
-    }
+    try {
+      if (!form.valid) {
+        return fail(400, { form });
+      }
 
-    const signin = await auth.api.signInEmail({
-      body: {
-        email,
-        password,
-      },
-      asResponse: true,
-    });
+      const signin: Response = await auth.api.signInEmail({
+        body: {
+          email,
+          password,
+        },
+        asResponse: true,
+      });
 
-    const setCookieHeader = signin.headers.get('set-cookie');
-    if (setCookieHeader) {
-      const parsedCookie = setCookieHeader.split(';')[0];
-      const [name, encodedValue] = parsedCookie.split('=');
-      // need to decode it first
-      const decodedValue = decodeURIComponent(encodedValue);
-      cookies.set(name, decodedValue, {
-        path: '/',
-        httpOnly: true,
-        sameSite: 'lax',
-        maxAge: 604800,
-        secure: !dev,
-      });
-    } else {
-      return setError(form, 'password', 'Invalid email or password', {
-        status: 401,
-      });
+      const setCookieHeader = signin.headers.get('set-cookie');
+      if (setCookieHeader) {
+        const parsedCookie = setCookieHeader.split(';')[0];
+        const [name, encodedValue] = parsedCookie.split('=');
+        // need to decode it first
+        const decodedValue = decodeURIComponent(encodedValue);
+        cookies.set(name, decodedValue, {
+          path: '/',
+          httpOnly: true,
+          sameSite: 'lax',
+          maxAge: 604800,
+          secure: !dev,
+        });
+      }
+    } catch (e) {
+      if ((e as APIError).body.code === 'INVALID_EMAIL_OR_PASSWORD') {
+        return setError(form, 'password', 'Invalid email or password', {
+          status: 401,
+        });
+      } else {
+        return setError(form, 'password', (e as APIError).body.code as string);
+      }
     }
 
     return message(form, 'Successfuly signed in.');