HHH-12778 Register the cause when an exception occurs creating a proxy

hibernate-core/src/main/java/org/hibernate/bytecode/internal/bytebuddy/BasicProxyFactoryImpl.java

@@ -54,7 +54,7 @@ public class BasicProxyFactoryImpl implements BasicProxyFactory {
 			return proxy;
 		}
 		catch (Throwable t) {
-			throw new HibernateException( "Unable to instantiate proxy instance" );
+			throw new HibernateException( "Unable to instantiate proxy instance", t );
 		}
 	}