time-config: fix warning for missing return in non-void function

Change-Id: Id2852a3a4dd48a59a37b847d97cc5de158335a82
Signed-off-by: Patrick Williams <patrick@stwcx.xyz>
diff --git a/time-config.cpp b/time-config.cpp
index 48bcbd4..b46ff54 100644
--- a/time-config.cpp
+++ b/time-config.cpp
@@ -3,6 +3,7 @@
 #include <iostream>
 #include <memory>
 #include <mapper.h>
+#include <cassert>
 #include "time-manager.hpp"
 
 std::map<std::string, TimeConfig::FUNCTOR> TimeConfig::iv_TimeParams = {
@@ -47,7 +48,7 @@
 }
 
 // Accepts a timeMode enum and returns it's string value
-const char* TimeConfig::modeStr(const TimeConfig::timeModes timeMode)
+const char* TimeConfig::modeStr(TimeConfig::timeModes timeMode)
 {
     switch(timeMode)
     {
@@ -60,6 +61,9 @@
             return "MANUAL";
         }
     }
+
+    assert(false);
+    return nullptr;
 }
 
 // Given a owner string, returns it's equivalent owner enum
@@ -84,7 +88,7 @@
 }
 
 // Accepts a timeOwner enum and returns it's string value
-const char* TimeConfig::ownerStr(const timeOwners timeOwner)
+const char* TimeConfig::ownerStr(timeOwners timeOwner)
 {
     switch(timeOwner)
     {
@@ -105,6 +109,9 @@
             return "BOTH";
         }
     }
+
+    assert(false);
+    return nullptr;
 }
 
 // Returns the busname that hosts objPath