Using KISS_FFT on a microcontroller

Question

Im kinda new to the compilers concept.

a little context, im programing a microcontroler, im trying to use an IIS (MEMS) to read aceleration data, and then aplying a fft to the data, I start getting the data whit an interruption (interruption routine is defined as button_on_PA14_pressed)), I have setted the interruption and I can get the aceleration data whitout a problem, but the fft is not working (im using KISS_FFT https://github.com/mborgerding/k...) I get the following error:

IMAGE OF THE ERROR HERE

The code I used was:

#include "kiss_fft.h"
#include "kiss_fft_log.h"
#include "kiss_fftnd.h"
#include "kiss_fftndr.h"
#include "kiss_fftr.h"

#include "IIS2DH_driver.h"



int Z;
volatile kiss_fft_scalar Z_data[500]={0x0};
volatile kiss_fft_cpx Z_fft;

volatile a=3;

uint32_t LIM=94; 

//INTERRUPTION ROUTINE
static void button_on_PA14_pressed(void)
{
   for (int i=0;i<LIM;i++)
   {
       Z_data[i]=IIS_get_Z(); //get the data of the MEMS all this works fine, defined in the  IIS2DH_driver.h library
   }
   

   kiss_fftr_cfg cfg = kiss_fftr_alloc(LIM,0,NULL,NULL);
   
   kiss_fftr(cfg,&Z_data,&Z_fft);

}