Fixed a null ref exception in static sky when the default volume profile is invalid. (#278)

* Fixed a null ref exception in static sky when the default volume profile is invalid.

* Update changelog

Co-authored-by: sebastienlagarde <[email protected]>

Author: JulienIgnace-Unity

com.unity.render-pipelines.high-definition/CHANGELOG.md

@@ -567,6 +567,7 @@ and this project adheres to [Semantic Versioning](http://semver.org/spec/v2.0.0.
 - Fixed an error about procedural sky being logged by mistake.
 - Fixed shadowmask UI now correctly showing shadowmask disable
 - Made more explicit the warning about raytracing and asynchronous compute. Also fixed the condition in which it appears.
+- Fixed a null ref exception in static sky when the default volume profile is invalid.
 
 ### Changed
 - Improve MIP selection for decals on Transparents

com.unity.render-pipelines.high-definition/Runtime/Sky/StaticLightingSky.cs

@@ -132,7 +132,9 @@ void UpdateCurrentStaticLightingSky()
                 var profileSkyParameters = m_SkySettingsFromProfile.parameters;
 
                 var defaultVolume = HDRenderPipeline.GetOrCreateDefaultVolume();
-                defaultVolume.sharedProfile.TryGet(skyType, out SkySettings defaultSky);
+                SkySettings defaultSky = null;
+                if (defaultVolume.sharedProfile != null) // This can happen with old projects.
+                    defaultVolume.sharedProfile.TryGet(skyType, out defaultSky);
                 var defaultSkyParameters = defaultSky != null ? defaultSky.parameters : null; // Can be null if the profile does not contain the component.
 
                 // Seems to inexplicably happen sometimes on domain reload.