Audioboo fieldtype error after 2.7.8 update

I've updated a local site from perch 2.7.5 to 2.7.8. The site uses the audioboo field type and a field in my Perch blog app post.html template for the Audioboo URL. I'm getting this error on the blog post edit screen when the field is empty (most of my posts have an empty field for the audioboo URL).

Notice: Undefined index: path in C:\Users\Clive Walker\OneDrive\Documents\Websites\Websites A-D\CVW Web Design\perch\addons\fieldtypes\audioboo\audioboo.class.php on line 27

Debug info

Debug Message
SELECT u.*, r.* FROM perch2_users u, perch2_user_roles r WHERE u.roleID=r.roleID AND u.userEnabled=1 AND u.userID=1 AND u.userHash='24dadc017338ba69655778dae2176c56' LIMIT 1
UPDATE perch2_users SET userHash='42e51a54a31ca68f00956350eabedaf7' WHERE userID=1
SELECT p.privKey FROM perch2_user_privileges p
SELECT * FROM (SELECT DISTINCT settingID, settingValue FROM perch2_settings WHERE userID=1 OR userID=0 ORDER BY userID DESC) AS settings GROUP BY settingID
SELECT * FROM perch2_blog_authors WHERE authorEmail='xxx - removed -xxx' LIMIT 1
SELECT * FROM perch2_blog_sections ORDER BY sectionTitle ASC
SELECT * FROM perch2_blog_posts WHERE postID=38
Using template: \templates\blog\post.html
SELECT COUNT(*) FROM perch2_blog_comments WHERE commentStatus='PENDING'
SELECT * FROM perch2_categories c, perch2_category_sets s WHERE c.setID=s.setID AND s.setSlug='blog' ORDER BY catTreePosition ASC
Adding:
SELECT * FROM perch2_blog_authors ORDER BY authorFamilyName, authorGivenName ASC
Queries: 11
Array
(
    [type] => 8
    [message] => Undefined index: path
    [file] => C:\Users\Clive Walker\OneDrive\Documents\Websites\Websites A-D\CVW Web Design\perch\addons\fieldtypes\audioboo\audioboo.class.php
    [line] => 27
)

This is happening on some blog posts where the audioboo URL field is empty but not all of them. So far, have not been able to figure out why that is the case.

Do you know if the audioboo fieldtype needs updating?