catch exceptions as const

Signed-off-by: Patrick Williams <patrick@stwcx.xyz>
Change-Id: Ic8e6ade739bd5ea6e79cac6b9bb2b182748e10c8
diff --git a/extensions/openpower-pels/registry.cpp b/extensions/openpower-pels/registry.cpp
index 34ff268..3f4462f 100644
--- a/extensions/openpower-pels/registry.cpp
+++ b/extensions/openpower-pels/registry.cpp
@@ -694,7 +694,7 @@
 
             return entry;
         }
-        catch (std::exception& e)
+        catch (const std::exception& e)
         {
             log<level::ERR>("Found invalid message registry field",
                             entry("ERROR=%s", e.what()));
@@ -726,7 +726,7 @@
     {
         registry = nlohmann::json::parse(file);
     }
-    catch (std::exception& e)
+    catch (const std::exception& e)
     {
         log<level::ERR>("Error parsing message registry JSON",
                         entry("JSON_ERROR=%s", e.what()));