Paste bug with complex path

[justvanrossum]

Uncaught (in promise) RangeError: Maximum call stack size exceeded

The problem is with Fontra's use of the spread operator for arguments, which is not suitable for arbitrary length arrays, as explained here:

• https://stackoverflow.com/questions/63705432/maximum-call-stack-size-exceeded-when-using-the-dots-operator

[justvanrossum]

The next problem is the maximum websocket message size, although it can be customized with the max_msg_size argument of WebSocketResponse.

[justvanrossum]

Since paste selects the pasted items, we also run into #65.

[justvanrossum]

A large websocket message closes the connection. I wonder if we can propagate the error without closing the connection.