To enable EWL C++ Debug mode simply uncomment this line in the EWL Configuration header <ewlconfig> See C++ Switches, Flags and Defines for more information.
#define _EWL_DEBUG
Alternatively you can #define _EWL_DEBUG in a prefix file. Either way, you must rebuild your C++ library after flipping this switch. Convenience makefiles are provided under ewl/EWL_C++/ to make this task easier. After rebuilding the C++ library, rebuild your application and run it. If there are any errors, a std::logic_error will be thrown. If exceptions are disabled, then instead the error function __ewl_error(const char*) is called. This function can be defined by client code. There are some sample implementations in <ewlconfig>. The default simply calls fprintf and abort.