Error "toString()" failed at stringSlice (buffer.js:563:44) at Buffer.toString (buffer.js:629:10)

[syshu]

This is because fs.readFile() is trying to read a file exceeds the size of 256MB (See: nodejs/node#3175 While turning the buffer content to a string, this error happens.)
Log folders usually contains memory dump files which can be possibly larger than 256MB, and listAppLogFiles will check every file in the log folder in isApplogFile with fs.readFile, that's where the error happens.