Expect and document a more concrete exception type

As was proposed during review.

src/Monolog/Handler/StreamHandler.php

@@ -32,7 +32,7 @@ class StreamHandler extends AbstractProcessingHandler
     private $dirCreated;
 
     /**
-     * @param resource|string $stream         If a missing path can't be created, an Exception will be thrown on first write
+     * @param resource|string $stream         If a missing path can't be created, an UnexpectedValueException will be thrown on first write
      * @param string|int      $level          The minimum logging level at which this handler will be triggered
      * @param bool            $bubble         Whether the messages that are handled can bubble up the stack or not
      * @param int|null        $filePermission Optional file permissions (default (0644) are only for owner read/write)

tests/Monolog/Handler/StreamHandlerTest.php

@@ -203,7 +203,7 @@ class StreamHandlerTest extends TestCase
             );
         }
 
-        $this->expectException(\Exception::class);
+        $this->expectException(\UnexpectedValueException::class);
         $this->expectExceptionMessage('There is no existing directory at');
 
         $handler->handle($this->getRecord());