False `type_mismatch_argument` after reassigning variable from its array offset

[alexchexes]

PHPantom version

phpantom_lsp 0.8.0-dirty

Installation method

Pre-built binary from GitHub Releases

Operating system

Windows x86_64

Editor

VS Code

Bug description

PHPantom keeps an old array|false type after a variable is reassigned from one of its own array offsets.

Expected: after $value = $value[0], later uses of $value should not still be treated as the previous array|false result.

Actual: PHPantom reports type_mismatch_argument when $value is passed to string parameters.

Steps to reproduce

1. Use any supported PHP version.
2. Create a PHP file with:

<?php

function stripFlat(string $value): string
{
    $value = preg_split('/(, flat \d+.*)/u', $value, 0, PREG_SPLIT_DELIM_CAPTURE);
    $value = $value[0];

    $value = preg_split('/(, room \d+.*)/u', $value, 0, PREG_SPLIT_DELIM_CAPTURE);
    $value = $value[0];

    return trim($value);
}

3. Run diagnostics.

PHPantom reports:

8   Argument 2 ($subject) expects string, got array|false
11  Argument 1 ($string) expects string, got array|false

Error output or panic trace

.phpantom.toml

Additional context

Using a separate $parts variable avoids this false positive:

$parts = preg_split('/.../', $value, 0, PREG_SPLIT_DELIM_CAPTURE);
$value = $parts[0];

The issue appears when the same variable is reused for both the array result and the extracted string.

Binary source

Originally observed in the VS Code extension v0.5.0. Reproduced with the extension-cached GitHub Releases binary