Error emitted in receive() when data contains only one line

[onlyfang]

In function PythonShell.prototype.receive(), when data contains only one line, it is saved to lastLine by

var lastLine = lines.pop();

and lines[0] is undifined.

Code line 177

lines[0] = (this._remaining || '') + lines[0];

set lines[0] to be string 'undefined'. This will cause error to be throw at JSON.parse below.

Propose: change line 177 to

if (this._remaining) {
      lines[0] = this._remaining + lines[0];
}

[extrabacon]

The data must properly end with a "\n" in order to be processed as a message. It is possible that a single JSON object is larger than the stdout buffer, which would lead to this error. However, the fix is a bit more complex, since a very large object might trigger this multiple times. In this case, PythonShell.receive must keep on buffering until the end of the message (until the "\n" character is found).

I have a test to cover this scenario and a fix is on the way.