fiji_download_gui.pl: try to join threads before exiting also in case of errors

But the obvious solution fails... add a FIXME instead

fiji_download_gui.pl

@@ -85,6 +85,7 @@ sub main {
     my $logger = get_logger("");
     my $name   = $0;
     my @ARGV   = @_;
+    my $ret    = 0;
     $name =~ s/\.p[lm]//;
     $logger->debug("=== Starting new execution of $name ===");
     $logger->debug( sprintf( "%d argument(s)%s", scalar(@_), scalar(@_) > 0 ? ": @_" : "" ) );
@@ -135,7 +136,8 @@ sub main {
                     -title => 'Open FIJI settings failed!',
                     -text  => "$msg\n",
                 )->Show();
-                return;
+                $ret = 1;
+                goto bailout;
             }
             $self->{'settings'} = $tmp_settings;
         }
@@ -145,7 +147,8 @@ sub main {
     }
 
     if ( !defined ${ $self->{'settings_ini_name'} } ) {
-        return 1;
+        $ret = 1;
+        goto bailout;
     }
 
     if ( defined $ARGV[1] ) {
@@ -160,7 +163,8 @@ sub main {
                     -title => 'Open FIJI Tests failed!',
                     -text  => "$msg\n",
                 )->Show();
-                return;
+                $ret = 1;
+                goto bailout;
             }
             $self->{'tests'} = $tmp_tests;
         } else {
@@ -199,13 +203,14 @@ sub main {
 
     MainLoop;
 
+bailout: # FIXME: this should join threads... but doing that segfaults O_o
     # End the queue so the thread can die
     $qw->end();
     $worker_tid->join();
 bailout: # FIXME: this should be above the block above to join all threads... but doing that segfaults O_o
 
     $logger->trace("=== Stopping execution ===");
-    return 0;
+    return $ret;
 }
 
 sub _load_settings_prompt {