[PATCH] imap: avoid raising exception if client disconnects

[Eric Wong <e@80x24.org>]

This ought to save a few cycles if a client disconnects while
in the middle of a (UID) FETCH.  This avoids:

  Can't call method "git" on an undefined value at .../PublicInbox/IMAP.pm

errors in stderr.
---
 lib/PublicInbox/IMAP.pm | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/lib/PublicInbox/IMAP.pm b/lib/PublicInbox/IMAP.pm
index e7ea7f7f..9327100c 100644
--- a/lib/PublicInbox/IMAP.pm
+++ b/lib/PublicInbox/IMAP.pm
@@ -619,18 +619,19 @@ sub fetch_run_ops {
 sub fetch_blob_cb { # called by git->cat_async via git_async_cat
 	my ($bref, $oid, $type, $size, $fetch_arg) = @_;
 	my ($self, undef, $msgs, $range_info, $ops, $partial) = @$fetch_arg;
+	my $ibx = $self->{ibx} or return; # client disconnected
 	my $smsg = shift @$msgs or die 'BUG: no smsg';
 	if (!defined($oid)) {
 		# it's possible to have TOCTOU if an admin runs
 		# public-inbox-(edit|purge), just move onto the next message
-		warn "E: $smsg->{blob} missing in $self->{ibx}->{inboxdir}\n";
+		warn "E: $smsg->{blob} missing in $ibx->{inboxdir}\n";
 		return requeue_once($self);
 	} else {
 		$smsg->{blob} eq $oid or die "BUG: $smsg->{blob} != $oid";
 	}
 	my $pre;
 	if (!$self->{wbuf} && (my $nxt = $msgs->[0])) {
-		$pre = git_async_prefetch($self->{ibx}->git, $nxt->{blob},
+		$pre = git_async_prefetch($ibx->git, $nxt->{blob},
 						\&fetch_blob_cb, $fetch_arg);
 	}
 	fetch_run_ops($self, $smsg, $bref, $ops, $partial);