Buffer concat Error with v4.2.3

[calidion]

Buffer.concat(['hello', 'world']);
TypeError: buf.copy is not a function
at Function.Buffer.concat (buffer.js:238:9)
at repl:1:8
at REPLServer.defaultEval (repl.js:248:27)
at bound (domain.js:280:14)
at REPLServer.runBound as eval
at REPLServer. (repl.js:412:12)
at emitOne (events.js:82:20)
at REPLServer.emit (events.js:169:7)
at REPLServer.Interface._onLine (readline.js:210:10)
at REPLServer.Interface._line (readline.js:549:8)

[ChALkeR]

https://nodejs.org/api/buffer.html#buffer_class_method_buffer_concat_list_totallength:

Class Method: Buffer.concat(list[, totalLength])
list Array List of Buffer objects to concat

'hello' and 'world' are not Buffer objects.

[ChALkeR]

Internally, Node.js tries to call .copy method on those objects (Buffer objects have a .copy method), but there is no such method in your strings, of course. That's what the error tells you.

[calidion]

I would like to say that Buffer.concat should check it's arguments first before it starts to copy.
if the arguments are not what anticipated, no need to do further copy and throw an error called buf.copy is not a function.
it just makes me confused.
what more acceptable is 'String dected where Buffer is required'.