[FIX] RSA: can not instantiate abstract phpseclib3\Crypt\RSA class and try-catch unreadable keys
As requested by @kroky: "I propose you add a try/catch with check if file is readable, show error to the user and give them the option to copy-paste the keys in TIki." on Telegram.
We cannot read the private and public ssh files which triggers an exception, to avoid breaking the execution we added a try catch and check if the key is readable, otherwise we throw an exception and display an error use also telling him what to do to solve the problem.
Edited by Steven ngesera