Check for definedness of $self->brain in Hailo::Storage::*

This catches:

    $ perl -Ilib script/hailo --train /tmp/fooblaoeu
    Use of uninitialized value $db in concatenation (.) or string at lib/Hailo/Storage/SQL.pm line 52.
    Use of uninitialized value in -s at lib/Hailo/Storage/SQLite.pm line 31.

Changes

@@ -1,6 +1,7 @@
 0.05
     - Shuffle key tokens and don't reuse them. Should make for more random
       replies.
+    - Check for definedness of $self->brain in Hailo::Storage::*
 
 0.04 Fri Jan 29 17:48:49 GMT 2010
     - You know that bug we talked about being fixed in 0.03? It was

lib/Hailo/Storage/SQL.pm

@@ -47,7 +47,7 @@ sub _build_dbi_options {
     my ($self) = @_;
     my $dbd = $self->dbd;
     my $dbd_options = $self->dbd_options;
-    my $db = $self->brain;
+    my $db = $self->brain // '';
 
     my @options = (
         "dbi:$dbd:dbname=$db",

lib/Hailo/Storage/SQLite.pm

@@ -28,7 +28,7 @@ after stop_training => sub {
 
 sub _exists_db {
     my ($self) = @_;
-    return -s $self->brain;
+    return defined $self->brain and -s $self->brain;
 }
 
 __PACKAGE__->meta->make_immutable;