qa: resolving psalm issues

- remove unused variable
- add assertion to reduce possible types from `TEnumCase`
- use `TypeCombiner` to provide proper `Union` containing all literals

Signed-off-by: Maximilian Bösing <2189546+boesing@users.noreply.github.com>

src/Psalm/Internal/Type/SimpleAssertionReconciler.php

@@ -2963,7 +2963,6 @@ private static function reconcileValueOf(
 
         // For now, only enums are supported here
         foreach ($assertion_type->type->getAtomicTypes() as $atomic_type) {
-            $class_name = null;
             $enum_case_to_assert = null;
             if ($atomic_type instanceof TClassConstant) {
                 $class_name = $atomic_type->fq_classlike_name;
@@ -2990,6 +2989,7 @@ private static function reconcileValueOf(
             // For value-of<MyBackedEnum>, the assertion is meant to return *ANY* value of *ANY* enum case
             if ($enum_case_to_assert === null) {
                 foreach ($class_storage->enum_cases as $enum_case) {
+                    assert($enum_case->value !== null, 'Verified enum type above, value is either string or int.');
                     $reconciled_types[] = Type::getLiteral($enum_case->value);
                 }
 
@@ -3004,7 +3004,7 @@ private static function reconcileValueOf(
             $reconciled_types[] = Type::getLiteral($enum_case->value);
         }
 
-        return new Union($reconciled_types);
+        return TypeCombiner::combine($reconciled_types, $codebase, false, false);
     }
 
     /**