Bug: Undefined variable: csv_output/file in exported CSV

With define('WP_DEBUG', true); in wp-config.php some errors can be observed in exported CSV file. Also the file has an incomplete name e.g. _2013-06-26_12-50.csv:

Notice: Undefined variable: csv_output in /../wp-content/plugins/wp-email-capture/inc/exportcsv.php on line 15
Notice: Undefined variable: file in /../wp-content/plugins/wp-email-capture/inc/exportcsv.php on line 37
Name,E-Mail
[…]

Reason, variables are not yet defined before use.

Wrong:

$csv_output .= __('Name','WPEC').",".__('Email','WPEC');
[...]
$filename = $file."_".date("Y-m-d_H-i",time());

Suggested fixes:

$csv_output = __('Name','WPEC').",".__('Email','WPEC');
[...]
$file = 'WP_Email_Capture';
$filename = $file."_".date("Y-m-d_H-i",time());

Edit: Won’t start an own thread for this, a similar error is e.g. in file inc/display.php in line 52 where $display .= "<div.. should be $display = "<div.., it is shown if the shortcode is used.

http://ww.wp.xz.cn/extend/plugins/wp-email-capture/