Fix return type of yield from (#11236)

* Fix return type of yield from

* Fix

Author: danog

src/Psalm/Internal/Analyzer/Statements/Expression/YieldFromAnalyzer.php

@@ -67,9 +67,9 @@ public static function analyze(
                     ) {
                         $yield_from_type = $atomic_type->type_params[3];
                     } elseif ($atomic_type instanceof TArray) {
-                        $yield_from_type = $atomic_type->type_params[1];
+                        $yield_from_type = Type::getNull();
                     } elseif ($atomic_type instanceof TKeyedArray) {
-                        $yield_from_type = $atomic_type->getGenericValueType();
+                        $yield_from_type = Type::getNull();
                     }
                 } else {
                     $yield_from_type = Type::getMixed();

tests/GeneratorTest.php

@@ -184,6 +184,17 @@ function foo() : Generator {
                         takesString($s);
                     }',
             ],
+            'returnTypeArr' => [
+                'code' => '<?php
+                    function foo() : Generator {
+                        $result = yield from [2];
+                        /** @psalm-check-type-exact $result = null */;
+                    }
+                    function foo2() : Generator {
+                        $result = yield from [];
+                        /** @psalm-check-type-exact $result = null */;
+                    }',
+            ],
             'expectNonNullableTypeWithYield' => [
                 'code' => '<?php
                     function example() : Generator {