schema compilation BUGFIX NULL pointer dereference
diff --git a/src/tree_schema_compile.c b/src/tree_schema_compile.c
index f2326aa..1b44025 100644
--- a/src/tree_schema_compile.c
+++ b/src/tree_schema_compile.c
@@ -3930,7 +3930,9 @@
 
     return cs;
 error:
-    lysc_node_free(ctx->ctx, (struct lysc_node*)cs);
+    if (cs) {
+        lysc_node_free(ctx->ctx, (struct lysc_node*)cs);
+    }
     return NULL;
 
 #undef UNIQUE_CHECK