fix: Avoid redirecting to login with an incomplete configuration

[come-nc]

• Fix Handle incomplete saml configuration more gracefully #840

[CarlSchwan]

psalm need a bit of fixing but looks good

[artonge]

/backport to stable7

[backportbot]

The backport to stable7 failed. Please do this backport manually.

# Switch to the target branch and update it
git checkout stable7
git pull origin stable7

# Create the new backport branch
git checkout -b backport/1091/stable7

# Cherry pick the change from the commit sha1 of the change against the default branch
# This might cause conflicts, resolve them
git cherry-pick 3c2857e2

# Push the cherry pick commit to the remote repository and open a pull request
git push origin backport/1091/stable7

Error: Failed to clone repository: Failed to create working tree: Preparing worktree (new branch 'backport/1091/stable7')
fatal: not a valid object name: 'origin/stable7'

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Learn more about backports at https://docs.nextcloud.com/server/stable/go.php?to=developer-backports.

[blizzz]

/backport to stable-7