[TypeDeclaration] Prevent checking class like has external fully qual…

…ifieds when class like is null (#319)

rules-tests/TypeDeclaration/Rector/ClassMethod/AddVoidReturnTypeWhereNoReturnRector/Fixture/some_function.php.inc

@@ -0,0 +1,19 @@
+<?php
+
+namespace Rector\Tests\TypeDeclaration\Rector\ClassMethod\AddVoidReturnTypeWhereNoReturnRector\Fixture;
+
+function some_function()
+{
+}
+
+?>
+-----
+<?php
+
+namespace Rector\Tests\TypeDeclaration\Rector\ClassMethod\AddVoidReturnTypeWhereNoReturnRector\Fixture;
+
+function some_function(): void
+{
+}
+
+?>

rules/TypeDeclaration/TypeInferer/SilentVoidResolver.php

@@ -48,7 +48,7 @@ public function hasExclusiveVoid(ClassMethod | Closure | Function_ $functionLike
             return false;
         }
 
-        if ($this->externalFullyQualifiedAnalyzer->hasExternalFullyQualifieds($classLike)) {
+        if ($classLike instanceof Stmt\Class_ && $this->externalFullyQualifiedAnalyzer->hasExternalFullyQualifieds($classLike)) {
             return false;
         }