combining never/empty twice gives never (#5756)

src/Psalm/Internal/Type/TypeCombiner.php

@@ -332,6 +332,7 @@ class TypeCombiner
         }
 
         $has_empty = (int) isset($combination->value_types['empty']);
+        $has_never = false;
 
         foreach ($combination->value_types as $type) {
             if ($type instanceof TMixed
@@ -344,18 +345,21 @@ class TypeCombiner
             if (($type instanceof TEmpty || $type instanceof TNever)
                 && (count($combination->value_types) > 1 || count($new_types))
             ) {
+                $has_never = true;
                 continue;
             }
 
             $new_types[] = $type;
         }
 
-        if (!$new_types) {
+        if (!$new_types && !$has_never) {
             throw new \UnexpectedValueException('There should be types here');
+        } elseif (!$new_types && $has_never) {
+            $union_type = Type::getNever();
+        } else {
+            $union_type = new Union($new_types);
         }
 
-        $union_type = new Union($new_types);
-
         if ($from_docblock) {
             $union_type->from_docblock = true;
         }

src/Psalm/Type.php

@@ -2,6 +2,7 @@
 namespace Psalm;
 
 use Psalm\Plugin\EventHandler\Event\StringInterpreterEvent;
+use Psalm\Type\Atomic\TNever;
 use function array_merge;
 use function array_pop;
 use function array_shift;
@@ -301,6 +302,13 @@ abstract class Type
         return new Union([$type]);
     }
 
+    public static function getNever(): Union
+    {
+        $type = new TNever();
+
+        return new Union([$type]);
+    }
+
     public static function getBool(): Union
     {
         $type = new TBool;

tests/TypeCombinationTest.php

@@ -55,6 +55,15 @@ class TypeCombinationTest extends TestCase
                         return $type_name === "array";
                     }',
             ],
+            'NeverTwice' => [
+                '<?php
+                    /** @return no-return */
+                    function other() {
+                        throw new Exception();
+                    }
+
+                    rand(0,1) ? die() : other();',
+            ],
         ];
     }