Remove needless if.

resolves #516
diff --git a/src/lib_json/json_value.cpp b/src/lib_json/json_value.cpp
index 5adfef4..7b6c89a 100644
--- a/src/lib_json/json_value.cpp
+++ b/src/lib_json/json_value.cpp
@@ -502,8 +502,7 @@
     JSON_ASSERT_UNREACHABLE;
   }
 
-  if (comments_)
-    delete[] comments_;
+  delete[] comments_;
 
   value_.uint_ = 0;
 }