fullIfComponents

fn fullIfComponents(tree: Ast, info: full.If.Components) full.If {
    var result: full.If = .{
        .ast = info,
        .payload_token = null,
        .error_token = null,
        .else_token = undefined,
    };
    // if (cond_expr) |x|
    //              ^ ^
    const payload_pipe = tree.lastToken(info.cond_expr) + 2;
    if (tree.tokenTag(payload_pipe) == .pipe) {
        result.payload_token = payload_pipe + 1;
    }
    if (info.else_expr != .none) {
        // then_expr else |x|
        //           ^    ^
        result.else_token = tree.lastToken(info.then_expr) + 1;
        if (tree.tokenTag(result.else_token + 1) == .pipe) {
            result.error_token = result.else_token + 2;
        }
    }
    return result;
}