How to determine the cause of an SQLITE_MISUSE error in a C++ program?

I am just trying to get an example working to create a table in an SQLite database, but the sqlite3_exec() call is returning an SQLITE_MISUSE code (21). I have been unable to determine the cause of the error or find an explanation online. Does anyone have an idea?

The output of the code is:

Opened database successfully 21 SQL error:

The code is:

#include <iostream>
#include <sqlite3.h>
#include <cstdlib>

static int callback(void *NotUsed, int argc, char **argv, char **azColName){
    int i;
    for(i=0; i<argc; i++){
        std::cout << azColName[i] << " = " << (argv[i] ? argv[i] : "NULL") << std::endl;
    }
    return 0;
}

int main()
{   
    sqlite3* db;
    char* zErrMsg = 0;
    int rc;

    /* Open database */
    rc = sqlite3_open("test.db", &db);
    if( rc ){
        std::cout << "Can't open database: " << sqlite3_errmsg(db) << std::endl;
        exit(0);
    }else{
        std::cout << "Opened database successfully" << std::endl;
    }
    sqlite3_close(db);

    /* Create SQL statement */
    const char* sql = "CREATE TABLE COMPANY(ID INT PRIMARY KEY NOT NULL, NAME TEXT NOT NULL, AGE INT NOT NULL, ADDRESS CHAR(50), SALARY REAL)";

    /* Execute SQL statement */
    rc = sqlite3_exec(db, sql, callback, 0, &zErrMsg);
    if( rc != SQLITE_OK ){
        std::cout << rc << std::endl;
        std::cout << "SQL error: " << zErrMsg << std::endl;
        sqlite3_free(zErrMsg);
    }else{
        std::cout << "Table created successfully" << std::endl;
    }
    sqlite3_close(db);

    return 0;
}