What causes HardFault_Handler errors and inaccurate predictions in STM32 air quality monitoring Sys?

#include "main.h"
#include "stm32f7xx_hal.h"
#include "tinyml_model.h"

float input_data[3];
float output_data[1];

float read_temperature() { return 25.0; }
float read_humidity() { return 60.0; }
float read_gas_level() { return 150.0; }

int main(void) {
    HAL_Init();
    SystemClock_Config();

    while (1) {
        input_data[0] = read_temperature();
        input_data[1] = read_humidity();
        input_data[2] = read_gas_level();

        if (predict_air_quality(input_data, output_data) != 0) {
            printf("Inference error\n");
        } else {
            printf("Predicted AQI: %.2f\n", output_data[0]);
        }

        HAL_Delay(1000);
    }
}