KeyedArray gets combined when in code but not when set by user

[kkmuffme]

when I do this in VariableFetchAnalyzer.php

 if ($var_id === '$_FILES') {
            $values = [
                'name' => new Union([
                    new TString(),
                ]),
                'type' => new Union([
                    new TString(),
                ]),
                'size' => new Union([
                    new TInt(),
                ]),
                'tmp_name' => new Union([
                    new TNonEmptyString(),
                ]),
                'error' => new Union([
                    new TInt(),
                ]),
            ];

            if ($codebase_analysis_php_version_id >= 81000) {
                $values['full_path'] = new Union([
                    new TString(),
                ]);
            }

            $type = new TKeyedArray($values);

            $array_values = [
                'name' => new Union([
                    new TNonEmptyList(Type::getString()),
                ]),
                'type' => new Union([
                    new TNonEmptyList(Type::getString()),
                ]),
                'size' => new Union([
                    new TNonEmptyList(Type::getInt()),
                ]),
                'tmp_name' => new Union([
                    new TNonEmptyList(Type::getNonEmptyString()),
                ]),
                'error' => new Union([
                    new TNonEmptyList(Type::getInt()),
                ]),
            ];

            if ($codebase_analysis_php_version_id >= 81000) {
                $array_values['full_path'] = new Union([
                    new TNonEmptyList(Type::getString()),
                ]);
            }

            $array_type = new TKeyedArray($array_values);

            return new Union([$type, $array_type]);
        }

And run

$arg = $_FILES;
/** @psalm-trace $arg */;

I get incorrect type:

array{error: non-empty-list, name: non-empty-list, size: non-empty-list, tmp_name: non-empty-list, type: non-empty-list}

However when I do this in the file directly, I get the correct type:

/**
 * @param array{error: non-empty-list<int>, name: non-empty-list<string>, size: non-empty-list<int>, tmp_name: non-empty-list<non-empty-string>, type: non-empty-list<string>}|array{error: int, name: string, size: int, tmp_name: non-empty-string, type: string} $arg
 * @return void
 */
function hello( $arg ) {
    /** @psalm-trace $arg */;
}

$arg: array{error: int|non-empty-list, name: non-empty-list|string, size: int|non-empty-list, tmp_name: non-empty-list|non-empty-string, type: non-empty-list|string}

Is there something wrong with my code or is there a bug/maybe with a quick workaround?

[orklah]

Types in an Union are stored in an array with a Key that is defined by Atomic::getKey().

All arrays in Psalm share the Key "array", which means you just can't store two arrays in an Union. You have to combine them first through TypeCombiner