改进异常模板 和 修正 重复的页面trace输出

library/think/Error.php

@@ -81,7 +81,6 @@ class Error
             self::output($exception, $data);
         }
 
-        Log::save();
         // 禁止往下传播已处理过的异常
         return true;
     }

tpl/think_exception.tpl

@@ -192,9 +192,11 @@
             </div>
         
     </div>
+	<?php if(!empty($source)){?>
         <div class="source-code">
             <pre class="prettyprint lang-php"><ol start="<?php echo $source['first']; ?>"><?php foreach ((array) $source['source'] as $key => $value) { ?><li class="line-<?php echo $key + $source['first']; ?>"><code><?php echo htmlentities($value); ?></code></li><?php } ?></ol></pre>
         </div>
+	<?php }?>
         <div class="trace">
             <h2>Call Stack</h2>
             <ol>