conversion-gen: check for nil pkg in getManualConversionFunctions

Author: munnerz

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

@@ -145,6 +145,10 @@ type conversionFuncMap map[conversionPair]*types.Type
 
 // Returns all manually-defined conversion functions in the package.
 func getManualConversionFunctions(context *generator.Context, pkg *types.Package, manualMap conversionFuncMap) {
+	if pkg == nil {
+		glog.Warningf("Skipping nil package passed to getManualConversionFunctions")
+		return
+	}
 	glog.V(5).Infof("Scanning for conversion functions in %v", pkg.Name)
 
 	scopeName := types.Ref(conversionPackagePath, "Scope").Name