Remove deprecated is_method_error code

The is_method_error() function is no longer needed, instead a
try-catch block should be used instead.
Reference:
https://lists.ozlabs.org/pipermail/openbmc/2018-October/013696.html,

Change-Id: I1919ea33fc18be2b8afd51fb1f85ddef15041e7c
Signed-off-by: Adriana Kobylak <anoo@us.ibm.com>
diff --git a/activation.cpp b/activation.cpp
index a938b8b..73acc3d 100644
--- a/activation.cpp
+++ b/activation.cpp
@@ -205,9 +205,11 @@
     auto method = this->bus.new_method_call(VERSION_BUSNAME, path.c_str(),
                                             "xyz.openbmc_project.Object.Delete",
                                             "Delete");
-    auto mapperResponseMsg = bus.call(method);
-    // Check that the bus call didn't result in an error
-    if (mapperResponseMsg.is_method_error())
+    try
+    {
+        bus.call_noreply(method);
+    }
+    catch (const SdBusError& e)
     {
         log<level::ERR>("Error in Deleting image from image manager",
                         entry("VERSIONPATH=%s", path.c_str()));
diff --git a/ubi/item_updater_helper.cpp b/ubi/item_updater_helper.cpp
index 68162cb..a699d5f 100644
--- a/ubi/item_updater_helper.cpp
+++ b/ubi/item_updater_helper.cpp
@@ -3,6 +3,7 @@
 #include "item_updater_helper.hpp"
 
 #include <phosphor-logging/log.hpp>
+#include <sdbusplus/exception.hpp>
 
 namespace phosphor
 {
@@ -12,6 +13,7 @@
 {
 
 using namespace phosphor::logging;
+using sdbusplus::exception::SdBusError;
 
 void Helper::setEntry(const std::string& entryId, uint8_t value)
 {
@@ -69,10 +71,12 @@
     auto updateEnvVarsFile =
         "obmc-flash-bmc-updateubootvars@" + versionId + ".service";
     method.append(updateEnvVarsFile, "replace");
-    auto result = bus.call(method);
 
-    // Check that the bus call didn't result in an error
-    if (result.is_method_error())
+    try
+    {
+        bus.call_noreply(method);
+    }
+    catch (const SdBusError& e)
     {
         log<level::ERR>("Failed to update u-boot env variables",
                         entry("VERSIONID=%s", versionId.c_str()));
@@ -105,10 +109,12 @@
                                       SYSTEMD_INTERFACE, "StartUnit");
     auto mirrorUbootFile = "obmc-flash-bmc-mirroruboot.service";
     method.append(mirrorUbootFile, "replace");
-    auto result = bus.call(method);
 
-    // Check that the bus call didn't result in an error
-    if (result.is_method_error())
+    try
+    {
+        bus.call_noreply(method);
+    }
+    catch (const SdBusError& e)
     {
         log<level::ERR>("Failed to copy U-Boot to alternate chip");
     }