fix: uncaught error in read device identification

[everhardt]

I ran into the following error when communicating with a solar logger over Modbus TCP:

RangeError [ERR_OUT_OF_RANGE]: The value of "offset" is out of range. It must be >= 0 and <= 12. Received 43
     at __node_internal_captureLargerStackTrace (node:internal/errors:490:5)
     at new NodeError (node:internal/errors:399:5)
     at boundsError (node:internal/buffer:88:9)
     at Buffer.readUInt8 (node:internal/buffer:254:5)
     at _readFC43 (/app/node_modules/modbus-serial/index.js:267:40)
     at ModbusRTU._onReceive (/app/node_modules/modbus-serial/index.js:538:13)
     at TcpPort.emit (node:events:513:28)
     at Socket.<anonymous> (/app/node_modules/modbus-serial/ports/tcpport.js:122:22)
     at Socket.emit (node:events:513:28)
     at addChunk (node:internal/streams/readable:324:12)
     at readableAddChunk (node:internal/streams/readable:297:9)
     at Readable.push (node:internal/streams/readable:234:10)
     at TCP.onStreamRead (node:internal/stream_base_commons:190:23)

Two problems here:

1. the error was uncaught, ie. it crashed my program
2. there are two interpretations of numOfObjects: the number of objects in the response or the number of objects in all responses combined. The spec states the former, but the example on page 45 shows the latter. The solar logger I was communicating with apparently uses the latter as well.

This PR addresses both problems.

[yaacov]

thanks 💚