ipapi.get now returns None if there are no InteractiveShells running.

It used to simply raise an IndexError, which was bad.

IPython/core/ipapi.py

@@ -18,16 +18,19 b' has been made into a component, this module will be sent to deathrow.'
 # Imports
 #-----------------------------------------------------------------------------
 
-from IPython.core.error import TryNext, UsageError
+from IPython.core.error import TryNext, UsageError, IPythonCoreError
 
 #-----------------------------------------------------------------------------
 # Classes and functions
 #-----------------------------------------------------------------------------
 
+
 def get():
     """Get the most recently created InteractiveShell instance."""
     from IPython.core.iplib import InteractiveShell
     insts = InteractiveShell.get_instances()
+    if len(insts)==0:
+        return None
     most_recent = insts[0]
     for inst in insts[1:]:
         if inst.created > most_recent.created: