Fix diffs when resource does not yet exist

Author: willthames

kustomize/resource_kustomization.go

@@ -190,6 +190,11 @@ func kustomizationResourceDiff(d *schema.ResourceDiff, m interface{}) error {
 		return nil
 	}
 
+	srcJSON := originalJSON.(string)
+	if srcJSON == "" {
+		return nil
+	}
+
 	desiredJSON := modifiedJSON.(string)
 	if desiredJSON == "" {
 		return nil