spawn: improve error checking for fork failures

fork failures are unfortunately common when Xapian has
gigabytes and gigabytes mmapped.

1 files changed, 1 insertions, 0 deletions

diff --git a/script/public-inbox-mda b/script/public-inbox-mda
index 145aa710..013642d0 100755
--- a/script/public-inbox-mda
+++ b/script/public-inbox-mda
@@ -97,6 +97,7 @@ sub do_spamc {
         my ($in, $out) = @_;
         my $rdr = { 0 => fileno($in) };
         my ($fh, $pid) = popen_rd([qw/spamc -E --headers/], undef, $rdr);
+        defined $pid or die "failed to popen_rd spamc: $!\n";
         my $r;
         do {
                 $r = sysread($fh, $$out, 65536, length($$out));