Segfault when two variables follow each other about tinyexpr HOT 4 CLOSED

int varsCount = 0;
        for (int i = 0; i < FORMULA_SIZE; i++)
        {
            if (formula[i] == 't')
                varsCount++;
        }

int varCount = 1;

te_variable vars[] = {{"t", &t, TE_VARIABLE}};
expr = te_compile("tt + 0", vars, 2, 0); //seg fault

te_variable vars[] = {{"t", &t, TE_VARIABLE}};
expr = te_compile("tt + 0", vars, 1, 0); //no seg fault

int main()
{
    int t = 0;
    te_expr *expr;
    int err = 0;

    te_variable vars[] = {{"t", &t, TE_VARIABLE}};

    int FORMULA_SIZE = 126;
    char formula[FORMULA_SIZE];
    memset(formula, 0, FORMULA_SIZE);
    char *initStr = "tt + 0";
    strncpy(formula, initStr, strlen(initStr));
    for (int i = 0; i < FORMULA_SIZE; i++)
    {
        if (formula[i] == '\0')
        {
            formula[i] = ' ';
        }
    }
    formula[FORMULA_SIZE - 1] = 0;

    while (t < 100000)
    {
        int varsCount = 0;
        for (int i = 0; i < FORMULA_SIZE; i++)
        {
            if (formula[i] == 't')
                varsCount++;
        }

        printf("vars: %d\n", varsCount);
        printf("tinyExpr formula: %s\n", formula);

        expr = te_compile(formula, vars, varsCount, 0);

        if (expr)
        {
            unsigned char result = te_eval(expr);
        }
        else
        {
            printf("parse error at %d\n", err);
        }
        t++;
    }

    te_free(expr);
}