Incorrect error message + error log entry when trying to upload smiley to folder with missing permissions

[sagamusix]

Description

When trying to upload a smiley to a smiley set whose folder is not writable by the web server, only the first character of the folder name is displayed in the user-facing error message, and in addition a PHP warning entry is added to the error log.

Steps to reproduce

1. Try to upload a new smiley to a smiley set that is not writable
2. The user-facing error message tells me that folder a and f are not writable (I was trying to upload a smiley to the alienine and fugue sets)
3. Error log entry is generated: Action /index.php?action=admin;area=smileys;sa=editsmileys, location Sources/ManageSmileys.php (Line 1030), error message: 2: Illegal string offset 'path'

Environment (complete as necessary)

• Version/Git revision: 2.1.2
• Database Type: MySQL
• PHP Version: 7.3