App: Handle uncleared Python exceptions during object restoration

When a Python-based object throws an exception during the restoration
process (e.g. inside `onDocumentRestored`), the error is caught by a
generic `catch(...)` block in `Document::afterRestore`.

Previously, this block swallowed the C++ exception wrapper but failed to
clear the underlying Python error state. Leaving the interpreter in this
"dirty" state caused a segmentation fault or `SystemError` later in the
loading process when C++ attempted to interact with the Python API
(specifically in `App::Application::setActiveDocument`).

This commit adds a check for `PyErr_Occurred()` inside the catch block.
If an error is detected, the traceback is printed to the console for
debugging, and `PyErr_Clear()` is called to reset the interpreter state,
allowing the application to continue loading the document without
crashing.

(cherry picked from commit b571889ab5)

src/App/Document.cpp

@@ -2092,6 +2092,16 @@ bool Document::afterRestore(const std::vector<DocumentObject*>& objArray, bool c
             FC_ERR("Failed to restore " << obj->getFullName() << ": " << e.what());
         }
         catch (...) {
+
+            // If a Python exception occurred, it must be cleared immediately.
+            // Otherwise, the interpreter remains in a dirty state, causing
+            // Segfaults later when FreeCAD interacts with Python.
+            if (PyErr_Occurred()) {
+                Base::Console().error("Python error during object restore:\n");
+                PyErr_Print(); // Print the traceback to stderr/Console
+                PyErr_Clear(); // Reset the interpreter state
+            }
+
             d->addRecomputeLog("Unknown exception on restore", obj);
             FC_ERR("Failed to restore " << obj->getFullName() << ": " << "unknown exception");
         }