clientHeight error on resourceTimeLine (Svelte 5)

[WoutPitje]

I get this error:

@event-calendar_resource-timeline.js?v=12892e86:223 Uncaught (in promise) TypeError: Cannot read properties of undefined (reading 'clientHeight')
at Array. (@event-calendar_resource-timeline.js?v=12892e86:223:34)
at run_all (chunk-OC2HZMU7.js?v=12892e86:28:11)
at $effect (chunk-VBIQWZ5S.js?v=12892e86:2620:7)
at update_reaction (chunk-OC2HZMU7.js?v=12892e86:889:23)
at update_effect (chunk-OC2HZMU7.js?v=12892e86:980:21)
at flush_queued_effects (chunk-OC2HZMU7.js?v=12892e86:1051:7)
at flush_queued_root_effects (chunk-OC2HZMU7.js?v=12892e86:1039:7)
at flush_sync (chunk-OC2HZMU7.js?v=12892e86:1150:5)
at new Svelte4Component (chunk-3ES4SABR.js?v=12892e86:704:7)

Its thrown in here

 afterUpdate(() => {
  set(titleHeight, $_headerEl().clientHeight);
});

Does anyone know what i am doing wrong? Thanks in advance : )

[vkurko]

Can you provide a live demo please? CodeSandbox, StackBlitz, etc