Issue222868

<jpython session>

JPython 1.1 on java1.0.5 (JIT: kaffe.jit)
Copyright (C) 1997-1999 Corporation for National Research Initiatives
>>> a  
Traceback (innermost last):
  File "<console>", line 1, in ?
NameError: a
>>> a b
Traceback (innermost last):
  (no code object) at line 0
java.lang.NullPointerException
        at org.python.core.Py.printException(Py.java:786)
        at org.python.core.PyException.printStackTrace(PyException.java:77)
        at org.python.core.PyException.toString(PyException.java:97)
        at org.python.util.InteractiveInterpreter.showexception(InteractiveInterpreter.java:92)
        at org.python.util.InteractiveInterpreter.runsource(InteractiveInterpreter.java:53)
        at org.python.util.InteractiveInterpreter.runsource(InteractiveInterpreter.java:42)
        at org.python.util.InteractiveConsole.push(InteractiveConsole.java:84)
        at org.python.util.InteractiveConsole.interact(InteractiveConsole.java:63)
        at org.python.util.jpython.main(jpython.java:141)

java.lang.NullPointerException: java.lang.NullPointerException

</jpython session>

This seems related to bug #162 "Unterminated string in interpreter causes NPE",
which causes the same NPE and should be a SyntaxError.

Fixed in Py by checking that the syntax error text is set before printing it.