TypeError in node-imap

[david-jointech]

When running nylas-mail my log gets many of this error:

 TypeError: list[i].toLowerCase is not a function
    at Parser.parseFetch (/usr/share/nylas-mail/resources/app.asar/node_modules/isomorphic-core/node_modules/imap/lib/Parser.js:476:19)
    at Parser._resUntagged (/usr/share/nylas-mail/resources/app.asar/node_modules/isomorphic-core/node_modules/imap/lib/Parser.js:274:24)
    at Parser._parse (/usr/share/nylas-mail/resources/app.asar/node_modules/isomorphic-core/node_modules/imap/lib/Parser.js:141:16)
    at Parser._tryread (/usr/share/nylas-mail/resources/app.asar/node_modules/isomorphic-core/node_modules/imap/lib/Parser.js:86:15)
    at Parser._parse (/usr/share/nylas-mail/resources/app.asar/node_modules/isomorphic-core/node_modules/imap/lib/Parser.js:166:10)
    at Parser._tryread (/usr/share/nylas-mail/resources/app.asar/node_modules/isomorphic-core/node_modules/imap/lib/Parser.js:86:15)
    at TLSSocket.Parser._cbReadable (/usr/share/nylas-mail/resources/app.asar/node_modules/isomorphic-core/node_modules/imap/lib/Parser.js:55:12)
    at emitNone (events.js:86:13)
    at TLSSocket.emit (events.js:185:7)
    at emitReadable_ (_stream_readable.js:432:10)
    at emitReadable (_stream_readable.js:426:7)
    at readableAddChunk (_stream_readable.js:187:13)
    at TLSWrap.onread (net.js:543:20)
    at Socket.ondata (_stream_wrap.js:58:20)
    at emitOne (events.js:96:13)
    at Socket.emit (events.js:188:7)
    at readableAddChunk (_stream_readable.js:176:18)
    at TCP.onread (net.js:543:20) message: 'list[i].toLowerCase is not a function' } { url: '/usr/share/nylas-mail/resources/app.asar/node_modules/isomorphic-core/node_modules/imap/lib/Parser.js',
  line: 476,
  column: 19,
  pluginIds: [] 

At the same time five of my Inboxes aren't syncing their folders (Inbox and new messages are working, just the old messages in the folders don't get loaded). These Inboxes are the only ones of my inboxes connected via SSL (imap.strato.de:993), the others are connected via Starttls (Port 143).
Are these errors maybe connected?
This issue in the original repository seems to be related: nylas/nylas-mail#3507