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## Environment
**Liquibase Version**: 3.10

**Database Vendor & Version**: any

**Operating System Type & Version**: any

## Description
Create a custom change with a params list where there is no "name", it will trigger a NullPointerException instead of a nicer validation error explaining the problem.

## Steps To Reproduce
A changelog file with the following customChange:

```
     - customChange:
         class: com.company.customchanges.AddAttribute
         param:
           fieldType: '12'
           mandatory: '1'
           labelKey: userAttribute.firstName
           maxLength: '50'
           index: '2'
           newline: '1'
           readOnly: '1'
           visible: '1'
```

which **was generated by the Liquibase YamlChangelogSerializer!!** (which is a separate issue)
trriggered a NullPointerException.

## Actual Behavior
A NullPointerException without a message.

## Expected/Desired Behavior
A clearer validation error should be thrown indicating the cause of the problem.


try {
            configureCustomChange();
            if (customChange instanceof CustomSqlChange) {
                statements = ((CustomSqlChange) customChange).generateStatements(database);
            } else if (customChange instanceof CustomTaskChange) {
                ((CustomTaskChange) customChange).execute(database);
            } else {
                throw new UnexpectedLiquibaseException(customChange.getClass().getName() + " does not implement " + CustomSqlChange.class.getName() + " or " + CustomTaskChange.class.getName());
            }
        } catch (CustomChangeException e) {
            throw new UnexpectedLiquibaseException(e);
        }
        if (statements == null) {
            statements = new SqlStatement[0];
        }
        return statements;
    }
    /**
     * Finishes configuring the CustomChange based on the values passed to {@link #setParam(String, String)} then calls {@link CustomSqlRollback#generateRollbackStatements(liquibase.database.Database)}
     * or {@link CustomTaskRollback#rollback(liquibase.database.Database)} depending on the CustomChange implementation.
     * <p></p>
     * If the CustomChange returns a null SqlStatement array, this method returns an empty array. If a CustomTaskChange is being used, this method will return an empty array.
     * Any {@link RollbackImpossibleException} exceptions thrown by the CustomChange will thrown by this method.
     */
    @Override
    public SqlStatement[] generateRollbackStatements(Database database) throws RollbackImpossibleException {
        SqlStatement[] statements = null;
        try {
            configureCustomChange();
            if (customChange instanceof CustomSqlRollback) {