Formula number formatting branch reported unreachable

[rafageist]

From PHPStan baseline: src/div.php line 5012.

Snippet:
`
if ( === null) {
...
continue;
}

if ( !== '' && is_numeric()) {
...
} else {
...
}
`

PHPStan reports if ( !== '' && is_numeric()) as unreachable. Investigate preceding logic or type inference for $format/$r.