Add proper error handling for PyObject.getPointer() from jpy

[devinrsmith]

No description provided.

[devinrsmith]

Here is the nice exception, instead of silent corruption and potential SIGSEGV:

server_1      | java.lang.RuntimeException: Error in Python interpreter:                                                                                                                                                                        
server_1      | Type: <class 'RuntimeError'>                                                                                                                                                                                                    
server_1      | Value: java.lang.IllegalStateException: PyObjectState has already been taken                                                                                                                                                    
server_1      |         at org.jpy.PyObjectState.borrowPointer(PyObjectState.java:28)                                                                                                                                                           
server_1      |         at org.jpy.PyObject.getPointer(PyObject.java:165)                                                                                                                                                                       
server_1      |         at org.jpy.PyLib.callAndReturnValue(Native Method)                                                                                                                                                                      
server_1      |         at org.jpy.PyProxyHandler.invoke(PyProxyHandler.java:120)                                                                                                                                                               
server_1      |         at io.deephaven.engine.util.$Proxy6.create_change_list(Unknown Source)                                                                                                                                                  
server_1      |         at io.deephaven.engine.util.PythonDeephavenSession.createDiff(PythonDeephavenSession.java:235)                                                                                                                          
server_1      |         at io.deephaven.engine.util.PythonDeephavenSession.createDiff(PythonDeephavenSession.java:49)                                                                                                                           
server_1      |         at io.deephaven.engine.util.AbstractScriptSession.applyDiff(AbstractScriptSession.java:136)                                                                                                                             
server_1      |         at io.deephaven.engine.util.AbstractScriptSession.incrementalSnapshot(AbstractScriptSession.java:121)                                                                                                                   
server_1      |         at io.deephaven.engine.util.AbstractScriptSession.reproFailure(AbstractScriptSession.java:113)                                                                                                                          
server_1      |         at io.deephaven.server.console.ConsoleServiceGrpcImpl.lambda$initializeGlobalScriptSession$0(ConsoleServiceGrpcImpl.java:128)                                                                                           
server_1      |         at java.base/java.lang.Thread.run(Thread.java:829)