Abort is triggered in debug build due to logical error.

```
CREATE TABLE A(k UInt32, t UInt32, a UInt64) ENGINE = MergeTree() ORDER BY (k, t);
INSERT INTO A(k,t,a) VALUES (1,101,1),(1,102,2),(1,103,3),(1,104,4),(1,105,5);

CREATE TABLE B(k UInt32, t UInt32, b UInt64) ENGINE = MergeTree() ORDER BY (k, t);
INSERT INTO B(k,t,b) VALUES (1,102,2), (1,104,4);

SELECT 
    (257, NULL, NULL), 
    (1, -2), 
    (-2, 7), 
    ('102.5', '0.03', NULL, NULL, NULL), 
    A.k, 
    toString((10, 0), 10.000100135803223), 
    A.a, 
    B.b, 
    toString(B.t), 
    B.k
FROM A
ASOF INNER JOIN B ON (A.k = B.k) AND NULL AND greaterOrEquals(B.t)
ORDER BY tuple(A.k) ASC;


Received exception from server (version 20.7.1):
Code: 1001. DB::Exception: Received from localhost:9000. DB::Exception: St12out_of_range: vector. 
```

{
    if (func.name == "and")
        return; 
    if (func.name == "equals")
    {
        if (func.arguments->children.size() != 2)
        {
            throwSyntaxException("Function 'equals' takes two arguments, got '"
                + func.formatForErrorMessage() + "' instead.");
        }
        ASTPtr left = func.arguments->children.at(0);
        ASTPtr right = func.arguments->children.at(1);
        auto table_numbers = getTableNumbers(ast, left, right, data);
        data.addJoinKeys(left, right, table_numbers);
        return;
    }
    ASOF::Inequality inequality = ASOF::getInequality(func.name);
    if (data.is_asof && (inequality != ASOF::Inequality::None))
    {
        if (data.asof_left_key || data.asof_right_key)
            throwSyntaxException("ASOF JOIN expects exactly one inequality in ON section, unexpected " + queryToString(ast) + ".");
        ASTPtr left = func.arguments->children.at(0);
        ASTPtr right = func.arguments->children.at(1);
        auto table_numbers = getTableNumbers(ast, left, right, data);
        data.addAsofJoinKeys(left, right, table_numbers, inequality);
        return;
    }
    throwSyntaxException("Expected equals expression, got " + queryToString(ast) + ".");
}
void CollectJoinOnKeysMatcher::getIdentifiers(const ASTPtr & ast, std::vector<const ASTIdentifier *> & out)