catch exceptions as const

Signed-off-by: Patrick Williams <patrick@stwcx.xyz>
Change-Id: Id1b5054d3147c39d98309bc11ed7016d6909e2a6
diff --git a/control/zone.cpp b/control/zone.cpp
index 9efb0c7..49ee35c 100644
--- a/control/zone.cpp
+++ b/control/zone.cpp
@@ -589,7 +589,7 @@
             iArch(current);
         }
     }
-    catch (std::exception& e)
+    catch (const std::exception& e)
     {
         log<level::ERR>(e.what());
         fs::remove(path);