Avoid exceptions on fetching uninitialized names in ClassLikes

Similar to the behavior of `ClassLikes::classImplements()` (#5984),
the following methods will return a false/empty value in case a
specific class name has not been initialized yet:

+ `ClassLikes::classExtends()` returns `false`
+ `ClassLikes::getParentInterfaces()` returns `[]`

src/Psalm/Internal/Codebase/ClassLikes.php

@@ -613,6 +613,9 @@ public function classExtends(string $fq_class_name, string $possible_parent, boo
             return false;
         }
 
+        if (!$this->classlike_storage_provider->has($unaliased_fq_class_name)) {
+            return false;
+        }
         $class_storage = $this->classlike_storage_provider->get($unaliased_fq_class_name);
 
         if ($from_api && !$class_storage->populated) {
@@ -722,7 +725,9 @@ public function interfaceExtends(string $interface_name, string $possible_parent
     public function getParentInterfaces(string $fq_interface_name): array
     {
         $fq_interface_name = strtolower($fq_interface_name);
-
+        if (!$this->classlike_storage_provider->has($fq_interface_name)) {
+            return [];
+        }
         return $this->classlike_storage_provider->get($fq_interface_name)->parent_interfaces;
     }