catch exceptions as const

Signed-off-by: Patrick Williams <patrick@stwcx.xyz>
Change-Id: If18cc0293b52ce5f7f8e068688aa17d28ed27d50
diff --git a/command/session_cmds.cpp b/command/session_cmds.cpp
index aa20941..8d3f663 100644
--- a/command/session_cmds.cpp
+++ b/command/session_cmds.cpp
@@ -103,7 +103,7 @@
             return ipmi::ccSuccess;
         }
     }
-    catch (std::exception& e)
+    catch (const std::exception& e)
     {
         log<level::ERR>("Failed in getting session state property",
                         entry("service=%s", service.c_str()),
@@ -154,7 +154,7 @@
             }
         }
     }
-    catch (sdbusplus::exception::exception& e)
+    catch (const sdbusplus::exception::exception& e)
     {
         log<level::ERR>("Failed to fetch object from dbus",
                         entry("INTERFACE=%s", session::sessionIntf),
@@ -198,7 +198,7 @@
             return session::ccInvalidSessionId;
         }
     }
-    catch (std::exception& e)
+    catch (const std::exception& e)
     {
         log<level::ERR>("Failed to get session manager instance",
                         entry("ERRMSG=%s", e.what()));
@@ -263,7 +263,7 @@
             session::Manager::get().getSession(handler->sessionID);
         currentSessionPriv = currentSession->currentPrivilege();
     }
-    catch (sdbusplus::exception::exception& e)
+    catch (const sdbusplus::exception::exception& e)
     {
         log<level::ERR>("Failed to fetch object from dbus",
                         entry("INTERFACE=%s", session::sessionIntf),