Remove always true/false occurrences

Finder.php

@@ -699,24 +699,20 @@ public function getIterator(): \Iterator
      * The set can be another Finder, an Iterator, an IteratorAggregate, or even a plain array.
      *
      * @return $this
-     *
-     * @throws \InvalidArgumentException when the given argument is not iterable
      */
     public function append(iterable $iterator): static
     {
         if ($iterator instanceof \IteratorAggregate) {
             $this->iterators[] = $iterator->getIterator();
         } elseif ($iterator instanceof \Iterator) {
             $this->iterators[] = $iterator;
-        } elseif (is_iterable($iterator)) {
+        } else {
             $it = new \ArrayIterator();
             foreach ($iterator as $file) {
                 $file = $file instanceof \SplFileInfo ? $file : new \SplFileInfo($file);
                 $it[$file->getPathname()] = $file;
             }
             $this->iterators[] = $it;
-        } else {
-            throw new \InvalidArgumentException('Finder::append() method wrong argument type.');
         }
 
         return $this;