Fix Unity null propagation

Author: keveleigh

Assets/MixedRealityToolkit/Inspectors/Profiles/MixedRealityInputSystemProfileInspector.cs

@@ -211,10 +211,14 @@ protected override ServiceConfigurationProperties GetDataProviderConfigurationPr
         /// <inheritdoc/>
         protected override IMixedRealityServiceConfiguration GetDataProviderConfiguration(int index)
         {
-            var configurations = (target as MixedRealityInputSystemProfile)?.DataProviderConfigurations;
-            if (configurations != null && index >= 0 && index < configurations.Length)
+            MixedRealityInputSystemProfile targetProfile = target as MixedRealityInputSystemProfile;
+            if (targetProfile != null)
             {
-                return configurations[index];
+                var configurations = targetProfile.DataProviderConfigurations;
+                if (configurations != null && index >= 0 && index < configurations.Length)
+                {
+                    return configurations[index];
+                }
             }
 
             return null;