Fix getService fail on single host platform

Add exception handling in the getService() function to so that the
isMultiHost() function returns correct value for single and multi-host
platform.

Tested: check on single host platform
1. Press power button and check if it works properly
2. Press reset button and check if it work properly

Signed-off-by: Thang Q. Nguyen <thang@os.amperecomputing.com>
Change-Id: I5c7019fb27b6ccb795ada9c63e591ce8561ff70c
diff --git a/src/button_handler.cpp b/src/button_handler.cpp
index 054f642..4a477fa 100644
--- a/src/button_handler.cpp
+++ b/src/button_handler.cpp
@@ -129,12 +129,17 @@
     auto method = bus.new_method_call(mapperService, mapperObjPath, mapperIface,
                                       "GetObject");
     method.append(path, std::vector{interface});
-    auto result = bus.call(method);
-
-    std::map<std::string, std::vector<std::string>> objectData;
-    result.read(objectData);
-
-    return objectData.begin()->first;
+    try
+    {
+        auto result = bus.call(method);
+        std::map<std::string, std::vector<std::string>> objectData;
+        result.read(objectData);
+        return objectData.begin()->first;
+    }
+    catch (const sdbusplus::exception::exception& e)
+    {
+        return std::string();
+    }
 }
 size_t Handler::getHostSelectorValue()
 {