Discrepancy between expected and actual output

From manual page: https://php.net/language.types.string

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In Example #18, the expected output described in the documentation is:

string(1) "b"
bool(true)

Warning: Illegal string offset '1.0' in /tmp/t.php on line 7
string(1) "b"
bool(false)

Warning: Illegal string offset 'x' in /tmp/t.php on line 9
string(1) "a"
bool(false)
string(1) "b"
bool(false)

However, the actual output is:

string(1) "b"
bool(true)
Fatal error: Uncaught TypeError: Cannot access offset of type string on string in php-wasm run script:7
Stack trace:
#0 {main}
  thrown in php-wasm run script on line 7