[FIX] Accounting : Fix Object of class DateTime could not be converted to string and count(): Argument #1 () must be of type Countable|array, null given in

Ticket: https://avan.tech/item102751

These errors occur in two places: example.org/tiki-accounting_entry.php?bookId=ID (Book new entries) and example.org/tiki-accounting_stack.php?bookId=ID (Book into stack) when the "Book" button is clicked.

Note: The second error occurred when the first is repaired.

First error:

Error: Object of class DateTime could not be converted to string in lib\smarty_tiki\function.html_select_date.php:127

Second error:

count(): Argument #1 ($value) must be of type Countable|array, null given in temp\templates_c\en_basic^60dc9195b6b60927477db9a6fa1207dd411d5479_0.file.tiki-accounting_stack.tpl.php:159