catch exceptions as const

Signed-off-by: Patrick Williams <patrick@stwcx.xyz>
Change-Id: Id1b5054d3147c39d98309bc11ed7016d6909e2a6
diff --git a/control/json/manager.cpp b/control/json/manager.cpp
index 4315cf1..691c11f 100644
--- a/control/json/manager.cpp
+++ b/control/json/manager.cpp
@@ -80,7 +80,7 @@
         _loadAllowed = true;
         load();
     }
-    catch (std::runtime_error& re)
+    catch (const std::runtime_error& re)
     {
         // Restore saved available and active profiles
         _loadAllowed = false;