Describe the bug

I've got an old v3 project that I've been upgrading to v5. I had two components, a parent component that was rendering a table, and a child component that was rendering table rows. The child also had some markup that was invalid (a child outside the <tr> element), but v3 ran with no issues. However v5 throws an unhelpful "dom is null" error. Weirdly, this only happens once I add an event handler to the markup.

This took me quite a while to find, since the error was extremely unhelpful and did not point me in the right direction. To be clear I think a better error would be nice in dev mode, in prod it's fine as is.

Reproduction

https://svelte.dev/playground/a717f2e8e91e4117940ff4bf805c8e23?version=5.23.0

Logs

System Info

System:
    OS: Windows 11 10.0.26100
    CPU: (24) x64 AMD Ryzen 9 5900X 12-Core Processor
    Memory: 15.93 GB / 31.91 GB
  Binaries:
    Node: 22.5.1 - C:\Program Files\nodejs\node.EXE
    npm: 10.9.0 - C:\Program Files\nodejs\npm.CMD
    pnpm: 8.15.5 - ~\AppData\Local\pnpm\pnpm.CMD
  Browsers:
    Edge: Chromium (131.0.2903.86)
    Internet Explorer: 11.0.26100.1882

Severity

annoyance