PiFmAdv instantly exits when no audio is provided

[MrBoombastic]

Hi. I observed, that when you provide no audio option, PiFmAdv will instantly close itself. This behaviour was not present in earlier versions, I think. Here are the logs:

sudo ./pi_fm_adv --freq 108 
Carrier: 108.00 Mhz, VCO: 972.0 MHz, Multiplier: 50.625000, Divider: 9
Allocating physical memory: size = 4354048, mem_ref = 2, bus_addr = 5e681000, virt_addr = 0xb66de000
Master PLLA Locked
Outputting signal on GPIO 4.
PPM correction is 0.0000, divider is 2131.5789 (2131 + 2371*2^-12).
RDS Options:
RDS: 1, PI: 1234, PS: "PiFmAdv", PTY: 15
RT: "PiFmAdv: Advanced FM transmitter for the Raspberry Pi"
Starting to transmit on 108.0 MHz.
Alert: 66 samples over deviation
Terminating: cleanly deactivated the DMA engine and killed the carrier.

PiFmAdv is updated to the latest version.