mysql2 throw error instead of fit the default value

[xOldeVx]

I have a column with default value and not nullable, when I try to insert null value to this column i'm getting error Column 'isUsa' cannot be null, why mysql2 doesn't fit the default value instead of throw exception?

For example in sql query:

-- Insert without specifying isUsa, will default to 0
INSERT INTO users () VALUES ();

-- Insert with NULL value for isUsa, will be replaced with 0
INSERT INTO users (isUsa) VALUES (NULL);

This is the user table describe:

Field	Type	Null	Key	Default	Extra
isUsa	tinyint(1)	        NO		  0	
.....
.....

This is the backend snippet:

const addUserDB = async (user) => {
    const userQuery = 'INSERT INTO users (firstName, lastName, isUsa) VALUES (?, ?, ?)';

    await db.query(userQuery, [
        user.firstName,
        user.lastName,
        user.isUsa,
    ]);
}