catch exceptions as const

Signed-off-by: Patrick Williams <patrick@stwcx.xyz>
Change-Id: I6b8b02a80cc28bfc63428e999de5b2645ffe4cf0
diff --git a/virtualSensor.cpp b/virtualSensor.cpp
index b81201e..2efd867 100644
--- a/virtualSensor.cpp
+++ b/virtualSensor.cpp
@@ -794,7 +794,7 @@
              * exists */
             this->matches.emplace_back(std::move(matchOnRemove));
         }
-        catch (std::invalid_argument& ia)
+        catch (const std::invalid_argument& ia)
         {
             error("Failed to set up virtual sensor: {ERROR}", "ERROR", ia);
         }