[ONNX FE] Improve error handling during op registration (#14201)

src/frontends/onnx/frontend/src/core/graph.cpp

@@ -384,6 +384,21 @@ OutputVector Graph::make_ng_nodes(const Node& onnx_node) {
         std::rethrow_exception(std::current_exception());
     }
 
+    const size_t outputs_size = std::accumulate(std::begin(ng_subgraph_outputs),
+                                                std::end(ng_subgraph_outputs),
+                                                0,
+                                                [](const size_t lhs, const Output<ov::Node>& rhs) {
+                                                    return lhs + rhs.get_node()->get_output_size();
+                                                });
+    NGRAPH_CHECK(onnx_node.get_outputs_size() <= outputs_size,
+                 "Expected output number of ",
+                 onnx_node.op_type(),
+                 " node is ",
+                 onnx_node.get_outputs_size(),
+                 " while the implementation provides ",
+                 outputs_size,
+                 " outputs");
+
     set_friendly_names(onnx_node, ng_subgraph_outputs);
 
     for (std::size_t i{0}; i < onnx_node.get_outputs_size(); ++i) {

src/frontends/onnx/tests/conversion.cpp

@@ -82,3 +82,23 @@ TEST(ONNXConversionExtensionTest, custom_op_with_custom_domain) {
     }
     FAIL() << "Expected operation not found in the converted model";
 }
+
+TEST(ONNXConversionExtensionTest, custom_op_with_incorrect_numer_of_outputs_exception) {
+    const auto ext =
+        std::make_shared<onnx::ConversionExtension>("CustomAdd",
+                                                    "custom.op",
+                                                    [](const ov::frontend::NodeContext& node) -> ov::OutputVector {
+                                                        // the default constructor called, the op with 0 output created
+                                                        auto op = std::make_shared<ov::op::v1::Add>();
+                                                        return {op};
+                                                    });
+
+    auto fe = std::make_shared<ov::frontend::onnx::FrontEnd>();
+    fe->add_extension(ext);
+
+    const auto input_model = fe->load(CommonTestUtils::getModelFromTestModelZoo(
+        ov::util::path_join({TEST_ONNX_MODELS_DIRNAME, "missing_op_domain.onnx"})));
+
+    std::shared_ptr<ov::Model> model;
+    ASSERT_THROW(fe->convert(input_model), ov::Exception);
+}