Refusing clobbering of {HandleError} installed on externally supplied DBI handle

Not sure which module to blame here. But the error goes away by commenting this section of Dancer::Plugin::Database::Core.pm

``` perl
# To support the database_error hook, use DBI's HandleError option
#$settings->{dbi_params}{HandleError} = sub {
# my ($error, $handle) = @_;
# $hook_exec->('database_error', $error, $handle);
#};
```

[20564] error @0.028260> [hit #1]request to GET /login crashed: DBIx::Class::Storage::DBI::catch {...} (): DBI Connection failed: DBIx::Class::Storage::DBI::try {...} (): Refusing clobbering of {HandleError} installed on externally supplied DBI handle Dancer::Plugin::Database::Core::Handle=HASH(0x9101c68). Either remove the handler or use the 'unsafe' attribute. at /opt/my-app/lib/App.pm line 247 at /opt/my-app/lib/App.pm line 247 in /usr/local/share/perl/5.14.2/Dancer/Handler.pm l. 101