fix(admin-edit-ban): resolve PHPStan false positive

[Rushaway]

Description

Gate the IP-length/validity check on $postBanType === BanType::Ip alone, then nest the $_POST['ip']-dependent conditions inside, instead of re-checking the enum inside a compound && alongside a mixed-typed operand.

Before:

if ($error === 0 && empty($_POST['ip']) && $postBanType === BanType::Ip) {
    // Didn't type an IP
    $error++;
    $validationErrors['ip'] = 'You must type an IP';
} elseif ($error === 0 && $postBanType === BanType::Ip && !filter_var($_POST['ip'], FILTER_VALIDATE_IP)) {
    $error++;
    $validationErrors['ip'] = 'You must type a valid IP';
}

After:

if ($postBanType === BanType::Ip) {
    if ($error === 0 && empty($_POST['ip'])) {
        // Didn't type an IP
        $error++;
        $validationErrors['ip'] = 'You must type an IP';
    } elseif ($error === 0 && !filter_var($_POST['ip'], FILTER_VALIDATE_IP)) {
        $error++;
        $validationErrors['ip'] = 'You must type a valid IP';
    }
}

Also regenerates the PHPStan baseline to realign the two pre-existing entries (ternary.alwaysTrue, booleanNot.alwaysFalse) whose line numbers shifted after this change.

No behavior change — pure equivalence transform ($postBanType === BanType::Ip was already a common factor to both branches, just factored out as an outer gate).

Motivation and Context

#1540
PHPStan was flagging the previous compound condition as always-false dead code:

Result of && is always false.
Result of && is always false.
Strict comparison using === between BanType::Steam and BanType::Ip will always evaluate to false.

blocking CI on pages/admin.edit.ban.php.

Confirmed false positive via isolated repro: combining a re-check of $postBanType with a mixed-typed $_POST value in the same && expression, right after an earlier if/elseif/elseif/else chain that discriminates on $postBanType only in its first branch, causes PHPStan to mis-merge the type. Renaming the variable or precomputing a boolean flag did not resolve it; removing the compound && combination does.

Fixes #

How Has This Been Tested?

• Ran includes/vendor/bin/phpstan analyse --configuration=phpstan.neon --no-progress --error-format=github --memory-limit=1G locally — clean, no errors on pages/admin.edit.ban.php.
• Manual smoke test on a local instance: edited an IP-type ban with an empty IP field → "You must type an IP"; with a malformed IP → "You must type a valid IP"; with a valid IP → saves normally.
• Manual smoke test: edited a Steam-type ban → unaffected, IP block correctly skipped entirely.

Screenshots (if appropriate):

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)

Checklist:

• My code follows the code style of this project.
• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• I have read the [CONTRIBUTING](CONTRIBUTING.md) document.

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