Mojo::Promise timer chaining

[maros]

Documentation at https://metacpan.org/pod/Mojo::Promise#timer states that it should be possible to chain a timer to an existing promise.
Hence I would expect following code to produce output where the two timestamps are ten seconds apart.

use Mojo::Promise;
my $p1 = Mojo::Promise->new();
my $p2 = $p1
     ->then(sub { say time })
     ->timer(10)
     ->then(sub{ say time }); 
$p1->resolve;
$p2->wait;

However this exampe terminates immediately without waiting 10 seconds in-between the two outputs.

In comparison, the following code works as expected

use Mojo::Promise;
my $p1 = Mojo::Promise->new();
my $p2 = $p1
     ->then(sub { say time; Mojo::Promise->timer(10) })
     ->then(sub{ say time }); 
$p1->resolve;
$p2->wait;