Crash, solved.

[dagnall53]

I had issues with this crashing .
I think the issue is with core_esp8266_12s.c in \AppData\Local\Arduino15\packages\esp8266\hardware\esp8266\2.3.0\cores\esp8266\core_esp8266_i2s.c (at least that is the path on my machine)
Putting this solution here so others can find it:
(see also esp8266/Arduino#2590)

Corrected code: (line 143 on)

void ICACHE_FLASH_ATTR i2s_slc_end(){
  int x;               // part of edit below
  ETS_SLC_INTR_DISABLE();
  SLCIC = 0xFFFFFFFF;
  SLCIE = 0;
  SLCTXL &= ~(SLCTXLAM << SLCTXLA); // clear TX descriptor address
  SLCRXL &= ~(SLCRXLAM << SLCRXLA); // clear RX descriptor address
                       //     https://github.com/esp8266/Arduino/issues/2590
         for (x=0; x<SLC_BUF_CNT; x++) free(i2s_slc_buf_pntr[x]);
                       // end edit
}