Surveys: Changes are lost on save when editing a survey that contains errors

[ioannisj]

Bug Description

Bug description

When editing a survey that contains errors (e.g link is not https) and clicking “Save”, the app redirects the user back and all unsaved changes to the survey are lost.

This makes it frustrating for users who invest significant time creating surveys, as they must recreate their work from scratch after encountering this type of error.

How to reproduce

1. Edit an existing survey.
2. Add or edit a link question and enter a link with an invalid format (e.g http://www.google.com)
3. Click "Save"
4. Survey exits edit more, the following error is shown and changes are lost

Update survey failed: Link must be a URL to resource with one of these schemes [https, mailto]

Additional context

Debug info

- [ ] PostHog Cloud, Debug information: [please copy/paste from https://us.posthog.com/settings/project-details#variables or https://eu.posthog.com/settings/project-details#variables]
- [ ] PostHog Hobby self-hosted with `docker compose`, version/commit: [please provide]
- [ ] PostHog self-hosted with Kubernetes (deprecated, see [`Sunsetting Kubernetes support`](https://posthog.com/blog/sunsetting-helm-support-posthog)), version/commit: [please provide]

[ioannisj]

Found this old issue that's related: #18614