feat: api endpoints and xml sync for contingents data

src/BusProNet/Traits/TypeConversionTrait.php

@@ -19,7 +19,7 @@ trait TypeConversionTrait
 
     protected function stringToFloat(?string $string): ?float
     {
-        if (true === empty($string)) {
+        if (null === $string || '' === $string) {
             return null;
         }