Fixed merge error in Unlit shader and crash in SkyManager

ScriptableRenderPipeline/HDRenderPipeline/ShaderPass/ShaderPassForwardUnlit.hlsl

     BSDFData bsdfData = ConvertSurfaceDataToBSDFData(surfaceData);
 
     // TODO: we must not access bsdfData here, it break the genericity of the code!
-    float4 EvaluateAtmosphericScattering(posInput, float4(bsdfData.color + builtinData.emissiveColor, builtinData.opacity));
+    float4 outColor = EvaluateAtmosphericScattering(posInput, float4(bsdfData.color + builtinData.emissiveColor, builtinData.opacity));
 
 #ifdef DEBUG_DISPLAY
     // Same code in ShaderPassForward.shader

ScriptableRenderPipeline/HDRenderPipeline/Sky/SkyManager.cs

         {
             using (new ProfilingSample(cmd, "Opaque Atmospheric Scattering"))
             {
-                if(skySettings.atmosphericScatteringSettings.NeedFogRendering())
+                if(skySettings != null && skySettings.atmosphericScatteringSettings.NeedFogRendering())
                 {
                     CoreUtils.DrawFullScreen(cmd, m_OpaqueAtmScatteringMaterial);
                 }