Fix error propagation error in parsing. Semantic checker fix for compile result struct. Test cleanup

test/codegen/nested_if.golden

@@ -8,11 +8,11 @@ float4 vs_main(float3 pos : POSITION) : SV_POSITION
         }
         else 
         {
-            return float4(1.0f);
+            return float4(1.0f, 1.0f, 1.0f, 1.0f);
         }
         return float4(pos, 1.0f);
     }
 
-    return float4(0.0f);
+    return float4(0.0f, 0.0f, 0.0f, 0.0f);
 }