fix(database): use currentRow instead of customResultObject in getRowObject and add null fallback

[gr8man]

Fix two bugs in BaseResult::getRowObject() and BaseResult::getRowArray():

1. Wrong property comparison in getRowObject() — The method compared $n against $this->customResultObject (an array) instead of $this->currentRow (an int). Since $n !== [] is always true for any integer, the condition always entered the branch, making the isset() check the only effective guard. This caused inconsistent currentRow tracking between getRowArray() and getRowObject().

2. Missing null guard on row access — Both getRowArray() and getRowObject() accessed $result[$this->currentRow] without checking if the key exists, potentially triggering an Undefined array key warning when the stored currentRow points to a non-existent index.

Checklist:

• Securely signed commits
• Component(s) with PHPDoc blocks, only if necessary or adds value (without duplication)
• Unit testing, with >80% coverage
• User guide updated
• Conforms to style guide

[mergeable]

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[michalsn]

Neither test exercises the newly added ?? null fallback. When an invalid requested index such as 999 is passed, currentRow remains 0, so the methods return the first row exactly as they did before this change.

Please add tests that set $result->currentRow to an invalid index before calling getRowArray() and getRowObject(). Since currentRow is public, this is the scenario the fallback handles.

Also, if invalid stored cursors are now expected to return null, please apply the same handling consistently to getCustomRowObject() and getPreviousRow(), which can still emit "Undefined array key" warnings.