List of feature flags not showing up in project UI

What does this MR do and why?

This MR fixes the frontend part of not showing the feature flag list if the data is not of expected format.

References

#386431 (closed)

Screenshots or screen recordings

Before	After

How to set up and validate locally

1. Navigate to Project -> Deploy -> Feature flags.
2. Select View user lists and create a new list.
3. Create a new feature flag with the "Type" "User List".
4. Edit this feature flag and change the "Type" to "User IDs".
5. Don't enter anything in the "User IDs" comma seperated field.
6. Create the feature flag.
7. A warning should appear "Strategies parameters parameters are invalid"
8. Click on "cancel"
9. Now the overview of feature flags seems to be empty. Even tho it shows the current plan info e.g. "4/200" feature flags active.

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Related to #386431 (closed)