PHP 8.1 passing null to scalar arguments deprecated

[thekid]

After php/php-src#6475 has been merged, there are a couple of places that need fixing:

• strlen(): Passing null to parameter 1 ($string) of type string is deprecated" in ::strlen() (Reader.class.php, line 95, occured once)
• iconv(): Passing null to parameter 2 ($to_encoding) of type string is deprecated" in ::iconv() (TextWriter.class.php, line 76, occured once)
• iconv(): Passing null to parameter 2 ($to_encoding) of type string is deprecated" in ::iconv() (TextWriter.class.php, line 76, occured once)
• ReflectionClass::hasConstant(): Passing null to parameter 1 ($name) of type string is deprecated" in ReflectionClass::hasConstant() (XPClass.class.php, line 355, occured once)
• strlen(): Passing null to parameter 1 ($string) of type string is deprecated" in ::strlen() (Type.class.php, line 211, occured once)
• strlen(): Passing null to parameter 1 ($string) of type string is deprecated" in ::strlen() (Bytes.class.php, line 39, occured once)
• strlen(): Passing null to parameter 1 ($string) of type string is deprecated" in ::strlen() (Type.class.php, line 211, occured once)
• ucfirst(): Passing null to parameter 1 ($string) of type string is deprecated" in ::ucfirst() (Environment.class.php, line 122, occured once)

See https://wiki.php.net/rfc/deprecate_null_to_scalar_internal_arg

[thekid]

✅ https://github.com/xp-framework/core/actions/runs/564202676