Issue with Shift Function / WDT Reset on ESP8266

[henmel]

Thanks for a great library. I am running into a WDT Reset issue on my ESP8266 when using some of the library Shift functions.
It happens when I use the leds.ShiftUp() or leds.ShiftDown(), but works fine when using the leds.ShiftLeft() or leds.ShiftRight()
Using a provided example, please see below:

#include <FastLED.h>        //https://github.com/FastLED/FastLED
#include <LEDMatrix.h>      //https://github.com/Jorgen-VikingGod/LEDMatrix

// Change the next defines to match your matrix type and size
#define DATA_PIN            2

#define COLOR_ORDER         GRB
#define CHIPSET             WS2812B

// initial matrix layout (to get led strip index by x/y)
#define MATRIX_WIDTH        16
#define MATRIX_HEIGHT       16
#define MATRIX_TYPE         HORIZONTAL_ZIGZAG_MATRIX
#define MATRIX_SIZE         (MATRIX_WIDTH*MATRIX_HEIGHT)
#define NUMPIXELS           MATRIX_SIZE

// create our matrix based on matrix definition
cLEDMatrix<MATRIX_WIDTH, MATRIX_HEIGHT, MATRIX_TYPE> leds;

uint8_t hue;
int16_t counter;
void setup()
{
  // initial LEDs
  FastLED.addLeds<CHIPSET, DATA_PIN, COLOR_ORDER>(leds[0], leds.Size()).setCorrection(TypicalSMD5050);
  FastLED.setCorrection(TypicalLEDStrip);
  FastLED.setBrightness(127);
  FastLED.clear(true);
  delay(500);

  hue = 0;
  counter = 0;
}


void loop()
{
  //leds.ShiftLeft();
  leds.ShiftDown();
  leds.DrawPixel(0,0,CHSV(hue, 255, 255));
//  leds.DrawPixel(0,15,CHSV(hue, 255, 255));
//  leds.DrawPixel(15,0,CHSV(hue, 255, 255));
//  leds.DrawPixel(15,15,CHSV(hue, 255, 255));

  hue+=4;
  counter++;
  FastLED.delay(25);

}

I get the following error right after the boot.

16:01:39.557 ->  ets Jan  8 2013,rst cause:4, boot mode:(3,6)
16:01:39.557 -> 
16:01:39.557 -> wdt reset
16:01:39.557 -> load 0x4010f000, len 3584, room 16 
16:01:39.557 -> tail 0
16:01:39.557 -> chksum 0xb0
16:01:39.557 -> csum 0xb0
16:01:39.557 -> v2843a5ac
16:01:39.557 -> ~ld

Thanks again. Your help is greatly appreciated!

[AaronLiddiment]

I have just verified my original code, none of the variables go out of bounds. But it looks like you are using a modified version of my library and it wouldn't be the first time someone has created problems with their changes.
Sorry but I don't have the time to debug their versions. In my code the function that actually handles the ShiftUp with your Matrix type is "void HZNHSD(void)" which can be found in the LEDMatrix.h header file.