make code compile with tsc 4.4.3

[0815fox]

Newest version of tsc complains about two errors:

lib/server.ts:228:30 - error TS2352: Conversion of type 'RawData' to type 'string' may be a mistake because neither type sufficiently overlaps with the other. If this was intentional, convert the expression to 'unknown' first.
Type 'Buffer[]' is not comparable to type 'string'.

228 message = JSON.parse(msg as string);
~~~~~~~~~~~~~

lib/server.ts:277:30 - error TS2571: Object is of type 'unknown'.

277 message: e.message,

However, it needs to be discussed, if msg as string should be force-casted as I did for now, or if we better use the toString method. Did not find out, why, but the msg-Parameter not is of type RawData which is Buffer | ArrayBuffer | Buffer[] and not directly convertible to string anymore.

[tim-hellhake]

npm run prettier

[0815fox]

After running prettier on this branch there were no changes in the diff. Don't know why the build failed.