address code-gen issue https://github.com/kubernetes/code-generator/issues/7

staging/src/k8s.io/code-generator/cmd/conversion-gen/generators/conversion.go

@@ -291,7 +291,11 @@ func Packages(context *generator.Context, arguments *args.GeneratorArgs) generat
 		// Make sure our peer-packages are added and fully parsed.
 		for _, pp := range peerPkgs {
 			context.AddDir(pp)
-			getManualConversionFunctions(context, context.Universe[pp], manualConversions)
+			p := context.Universe[pp]
+			if nil == p {
+				glog.Fatalf("failed to find pkg: %s", pp)
+			}
+			getManualConversionFunctions(context, p, manualConversions)
 		}
 
 		unsafeEquality := TypesEqual(memoryEquivalentTypes)