An issue regarding multiple drivers on a wire, error: [DRC MDRV-1] Multiple Driver Nets: Net led_OBUF[0] has multiple drivers: led_OBUF[0]_inst_i_1/O

Question

I am creating a simple VHDL code which should create two 4 bit binary numbers (A and B) using 8 inputs (4 for each), then based on one of three buttons being pressed, a logi