[ZF2-454][zendframework/zendframework#2403] Logic tweaks

- Import Exception namespace, not individual exceptions
  - Update @throws annotation accordingly
- Throw early

src/Writer/FirePhp.php

@@ -13,7 +13,7 @@
 use FirePHP as FirePHPService;
 use Zend\Log\Formatter\FirePhp as FirePhpFormatter;
 use Zend\Log\Logger;
-use Zend\Log\Exception\RuntimeException;
+use Zend\Log\Exception;
 
 /**
  * @category   Zend
@@ -84,10 +84,17 @@ protected function doWrite(array $event)
      * Gets the FirePhpInterface instance that is used for logging.
      *
      * @return FirePhp\FirePhpInterface
-     * @throws Zend\Log\Exception\RuntimeException
+     * @throws Exception\RuntimeException
      */
     public function getFirePhp()
     {
+        if (!$this->firephp instanceof FirePhp\FirePhpInterface
+            && !class_exists('FirePHP')
+        ) {
+            // No FirePHP instance, and no way to create one
+            throw new Exception\RuntimeException('FirePHP Class not found');
+        }
+
         // Remember: class names in strings are absolute; thus the class_exists
         // here references the canonical name for the FirePHP class
         if (!$this->firephp instanceof FirePhp\FirePhpInterface
@@ -96,8 +103,6 @@ public function getFirePhp()
             // FirePHPService is an alias for FirePHP; otherwise the class
             // names would clash in this file on this line.
             $this->setFirePhp(new FirePhp\FirePhpBridge(new FirePHPService()));
-        } elseif (!class_exists('FirePHP')) {
-            throw new RuntimeException('FirePHP Class not found');
         }
 
         return $this->firephp;