ESP8266 + NeoPixel - Cannot set pixel color, I got "Exception 29: StoreProhibited"
Your "constructor" isn't doing what you think.

In the example you point to you have, efectively:

Class object = Class(parameters);


Whereas in your code you have:

Class object;

object = Class(parameters);


In the first form it results in a new object constructed at declaration time. In the second it first creates a new "empty" object and then at a later date tries to copy a newly constructed object into it - which may be failing if the class doesn't support copying.

Instead you should be working with new and pointers.

In your class definition you create a pointer to your Adafruit class:

private:
    Adafruit_NeoPixel *pixels;


Then you create a new object pointing to it:

pixels = new Adafruit_NeoPixel(numOfPixels, dataPin, NEO_GRB + NEO_KHZ800);


Accessing it is then done with -&gt; instead of .:

pixels-&gt;setPixelColor(i, red, green, blue);