For non-image file LibRaw will return LIBRAW_FILE_UNSUPPORTED return code.
This error is not 'fatal', so LIBRAW_FATAL_ERROR is 'false' for this return code.
It is better to compare return code with LIBRAW_SUCCESS.
dcraw_make_mem_thumb() will return NULL pointer to image variable, so image->data_size will result to memory access error.
For non-image file LibRaw will return LIBRAW_FILE_UNSUPPORTED return code.
This error is not 'fatal', so LIBRAW_FATAL_ERROR is 'false' for this return code.
It is better to compare return code with LIBRAW_SUCCESS.
dcraw_make_mem_thumb() will return NULL pointer to image variable, so image->data_size will result to memory access error.