Cannot read property 'executeQuery' of null - sveltekit

Question

Can anybody help me understand why i'm getting this error:
My setup :
New sveltekit project.
ASP.net core backend for graphql.
Querying was working before I modified it to include subscriptions.
error msg:
Cannot read property 'executeQuery' of null
TypeError: Cannot read property 'executeQuery' of null
at C:\Repos\AGScada\node_modules\#urql\svelte\dist\urql-svelte.js:234:11
at C:\Repos\AGScada\node_modules\wonka\dist\wonka.js:254:18
at Object.next (C:\Repos\AGScada\node_modules\wonka\dist\wonka.js:1161:14)
at C:\Repos\AGScada\node_modules\#urql\svelte\dist\urql-svelte.js:173:11
at Object.subscribe (C:\Repos\AGScada\node_modules\svelte\store\index.js:53:9)
at Object.subscribe (C:\Repos\AGScada\node_modules\#urql\svelte\dist\urql-svelte.js:96:14)
at C:\Repos\AGScada\node_modules\#urql\svelte\dist\urql-svelte.js:168:14
at C:\Repos\AGScada\node_modules\wonka\dist\wonka.js:1159:9
at C:\Repos\AGScada\node_modules\wonka\dist\wonka.js:247:7
at C:\Repos\AGScada\node_modules\wonka\dist\wonka.js:590:18
Source Code index.svelte:
import { setClient, query, operationStore, subscription } from '#urql/svelte';
import { createClient, defaultExchanges, subscriptionExchange } from '#urql/svelte';
import { createClient as createWSClient } from 'graphql-ws';
const wsClient = process.browser ? createWSClient({url: 'ws://localhost:5000/graphql',}):null;
const client = process.browser ? createClient({
url: 'http://localhost:5000/graphql',
exchanges: [
...defaultExchanges,
subscriptionExchange({
forwardSubscription: (operation) => ({
subscribe: (sink) => ({
unsubscribe: wsClient.subscribe(operation, sink),
}),
}),
}),
],
}): null;
let tags = operationStore(`query {tags{tagName value}}`);
let onTagUpdated = operationStore(`subscription {onTagUpdated{tagName value}}`);
query(tags);
subscription(onTagUpdated);
setClient(client);
if($tags.fetching)
{
console.log("loading");
}
else
{
console.log($tags.data);
}
Thankyou for any help.

Answer 1

I got sveltekit and URQL working with the subscription support.
Source can be found here:
https://github.com/ruban258/sveltekit_urql_test
import { Client, setClient, operationStore, subscription, defaultExchanges, subscriptionExchange, query, createClient } from '#urql/svelte';
import {SubscriptionClient} from 'subscriptions-transport-ws';
import { browser } from '$app/env';
import { createClient as createWSClient } from 'graphql-ws';
const subscriptionClient = browser ? new SubscriptionClient('ws://localhost:5000/graphql', { reconnect: true }): null;
const wsClient = browser? createWSClient({
url: 'ws://localhost:5000/graphql',
}):null;
const client = browser ? new Client({
url: 'http://localhost:5000/graphql',
exchanges: [
...defaultExchanges,
subscriptionExchange({
forwardSubscription: (operation) => subscriptionClient.request(operation)
}),
],
}): null;
const messages = operationStore(`
subscription onTagUpdated{
onTagUpdated{
tagName
value
}
}
`);
const tags = operationStore(`
query{
tags{
tagName
value
}
}
`);
const handleSubscription = (messages = [], data) => {
return [data.newMessages, ...messages];
};
setClient(client);