do not allow negative leading zeros (#812)

Author: frederikbosch

src/Number.php

@@ -225,7 +225,7 @@ private static function parseIntegerPart(string $number): string
             return '0';
         }
 
-        if ($number === '-') {
+        if ($number === '-' || $number === '-0') {
             return '-0';
         }
 
@@ -244,6 +244,10 @@ private static function parseIntegerPart(string $number): string
                 throw new InvalidArgumentException(sprintf('Invalid integer part %1$s. Invalid digit %2$s found', $number, $digit));
             }
 
+            if ($digit === '-') {
+                continue;
+            }
+
             if ($nonZero === false && $digit === '0') {
                 throw new InvalidArgumentException('Leading zeros are not allowed');
             }

tests/NumberTest.php

@@ -166,6 +166,7 @@ public static function invalidNumberExamples(): array
             [''],
             ['000'],
             ['005'],
+            ['-005'],
             ['123456789012345678-123456'],
             ['---123'],
             ['123456789012345678+13456'],