Fix PHPStan exceptions

phpstan.neon

@@ -16,9 +16,8 @@ parameters:
         - '#Call to an undefined method DateTimeInterface::setTimezone\(\)\.#'
         - '#should return (\S*)static\(Carbon\\CarbonInterval\)\|null but returns Carbon\\CarbonInterval(\|null)?\.$#'
         # - '#should return (\S*)static\(Carbon\\CarbonPeriod\) but returns Carbon\\CarbonPeriod\.$#'
-        - '#should return (\S*)static\(Carbon\\Carbon\) but returns Carbon\\Carbon(Interface)?\.$#'
-        - '#should return (\S*)static\(Carbon\\CarbonImmutable\) but returns Carbon\\Carbon(Immutable|Interface)\.$#'
-        - '#should return (\S*)static\(Carbon\\CarbonImmutable\)\|null but returns Carbon\\Carbon(Immutable|Interface)\|null\.$#'
+        - '#should return (\S*)static\(Carbon\\Carbon\)(\|null)? but returns Carbon\\Carbon(Interface)?(\|null)?\.$#'
+        - '#should return (\S*)static\(Carbon\\CarbonImmutable\)(\|null)? but returns Carbon\\Carbon(Immutable|Interface)(\|null)?\.$#'
         - '#^PHPDoc tag @return with type Carbon\\CarbonTimeZone is not subtype of native type static\(Carbon\\CarbonTimeZone\)\.$#'
         - '#^PHPDoc tag @mixin contains invalid type Carbon\\Traits\\DeprecatedProperties\.$#'
         - '#^Implementing PHPStan\\Reflection\\Php\\BuiltinMethodReflection is not covered by backward compatibility promise\.#'

src/Carbon/CarbonInterval.php

@@ -802,6 +802,8 @@ protected static function this(): static
      *
      * @param string $intervalDefinition
      *
+     * @throws InvalidIntervalException
+     *
      * @return static
      */
     public static function fromString(string $intervalDefinition): static

src/Carbon/Traits/Units.php

@@ -408,7 +408,6 @@ public function subtract($unit, $value = 1, ?bool $overflow = null): static
     private static function rawAddUnit(self $date, string $unit, int|float $value): ?static
     {
         try {
-
             if ($unit === 'microsecond' && version_compare(PHP_VERSION, '8.1.0-dev', '>=')) {
                 throw new UnsupportedUnitException($unit, '8.1'); // @codeCoverageIgnore
             }