Exceptions

All the exceptions are in the Silarhi\Cfonb\Exceptions namespace and extend RuntimeException.

Exception	Extends	Thrown
ParseException	RuntimeException	By parse(), on a line the reader cannot parse, or records out of order: messages
ValueOfKeyIsNotAStringException	ParseException	By parse(), on a blank required field
ValueOfKeyIsNotNumericException	ParseException	By parse(), on a blank numeric field
KeyDoesNotExistException	ParseException	Never in practice: an internal error of a line parser
BalanceUnavailableException	RuntimeException	By Statement::getOldBalance() and getNewBalance(), on a statement built by hand without them
HeaderUnavailableException	RuntimeException	By Transfer::getHeader(), on a transfer built by hand without one
TotalUnavailableException	RuntimeException	By Transfer::getTotal(), on a transfer built by hand without one

Catch ParseException around parse(): it covers its three subclasses.

use Silarhi\Cfonb\Cfonb120Reader;
use Silarhi\Cfonb\Exceptions\ParseException;

try {
    $statements = (new Cfonb120Reader())->parse($content);
} catch (ParseException $e) {
    // The file is not a valid CFONB 120 file
}

The statements and transfers returned by the readers always have their balances, header and total: the *UnavailableException exceptions are never thrown on them.