CORRECT007 · Lifecycle call outside component initialisation

Severity: critical · Category: correctness

What it checks

Flags calls to Svelte’s lifecycle and context functions (onMount, onDestroy, beforeUpdate, afterUpdate, createEventDispatcher, getContext, setContext, hasContext, getAllContexts — value-imported from svelte, aliases and namespace imports included) that are guaranteed to run outside component initialisation:

• at module scope in a .svelte.ts/.svelte.js runes module or a .svelte <script module> block,
• in the constructor of a class instantiated at module scope (same file),
• in a SvelteKit load function, form action, endpoint or hooks handler, or the init hook, or at the top level of such a file — the classic trap is getContext inside load.

Not flagged: calls inside ordinary functions (a component may legally call them during its own initialisation), createContext() (module-scope creation is the official pattern of the new context API), non-context svelte exports (mount, tick, …), same-named functions imported from other modules, factory functions/IIFEs/cross-file classes, and svelte/legacy’s createBubbler. A function defined inside a load/handler/init body is treated as running there too and inherits the flag — if you deliberately return such a closure for a component to call during its own initialisation, add an inline suppression (svelte-vitals-disable-next-line CORRECT007).

Why it matters

These functions require an active component context. Called without one they throw Svelte’s lifecycle_outside_component error at runtime — the compiler compiles all of these patterns without a warning, so the failure only surfaces when the code path runs, typically as a production crash (in a load function: a 500 on every visit to that route).

How to fix

+page.ts

import { getContext } from 'svelte';

export async function load({ fetch }) {
  const user = getContext('user'); // ❌ lifecycle_outside_component — load is not component init

  return { user: await (await fetch('/api/user')).json() }; // ✅ return data instead
}

Move the call into component initialisation:

+page.svelte

<script>
  import { setContext } from 'svelte';

  let { data } = $props();
  setContext('user', () => data.user); // ✅ component init — legal
</script>

For shared modules, expose a setup function that components call during init instead of running lifecycle calls at module scope.