App working locally but not on production: TypeError: Cannot read property 'titulo_categoria' of undefined - next.js

Question

I'm trying to deploy an app using Prismic as CMS and everything works perfectly locally, but once I deploy to vercel I get the error:
19:09:51.850 | TypeError: Cannot read property 'titulo_categoria' of undefined
There seems to be something wrong when it tries to get the data from Prismic.
My code is the following:
import {getAllCategorias, getCategory2} from '../../lib/api';
export default function Index({cat}) {
return <>{cat.titulo_categoria[0].text}</>;
}
export async function getStaticProps({params}) {
const data = await getCategory2(params.slug);
return {
props: {
cat: data?.categorias ?? null,
},
};
}
export async function getStaticPaths() {
const allPosts = await getAllCategorias();
return {
paths: allPosts?.map(({node}) => `/test/${node._meta.uid}`) || [],
fallback: true,
};
}
And the API code that gets data from Prismic is:
import Prismic from 'prismic-javascript';
const REPOSITORY = process.env.PRISMIC_REPOSITORY_NAME;
const REF_API_URL = `https://${REPOSITORY}.prismic.io/api/v2`;
const GRAPHQL_API_URL = `https://${REPOSITORY}.prismic.io/graphql`;
// export const API_URL = 'https://your-repo-name.cdn.prismic.io/api/v2'
export const API_TOKEN = process.env.PRISMIC_API_TOKEN;
export const API_LOCALE = process.env.PRISMIC_REPOSITORY_LOCALE;
export const PrismicClient = Prismic.client(REF_API_URL, {
accessToken: API_TOKEN,
});
async function fetchAPI(query, {previewData, variables} = {}) {
const prismicAPI = await PrismicClient.getApi();
const res = await fetch(
`${GRAPHQL_API_URL}?query=${query}&variables=${JSON.stringify(variables)}`,
{
headers: {
'Prismic-Ref': previewData?.ref || prismicAPI.masterRef.ref,
'Content-Type': 'application/json',
'Accept-Language': API_LOCALE,
Authorization: `Token ${API_TOKEN}`,
},
}
);
if (res.status !== 200) {
console.log(await res.text());
throw new Error('Failed to fetch API');
}
const json = await res.json();
if (json.errors) {
console.error(json.errors);
throw new Error('Failed to fetch API');
}
return json.data;
}
export async function getCategory2(slug) {
const data = await fetchAPI(
`
query CategoryBySlug($slug: String!, $lang: String!) {
categorias(uid: $slug, lang: $lang) {
titulo_categoria
_meta {
uid
}
}
}
`,
{
variables: {
slug,
lang: API_LOCALE,
},
}
);
return data;
}
Any idea what's wrong with this? I been trying to figure it out for the whole day without any luck

Answer 1

Perhaps you already checked that, but since you mentioned everything works locally and not on Vercel are you sure your environment variables are set there? Especially PRISMIC_API_TOKEN since it appears you're relying on it to query the API?
Also I'm a bit worried about that part of the code:
props: {
cat: data?.categorias ?? null,
}
...where you might be sending a null value to your Index component resulting in your error, I'd try that instead:
props: {
cat: data?.categorias ?? {},
}
...plus using the safe navigation operator (?.) on the Index component?
Let me know how it goes!