Robustness to incorrect types; numpy.int64 cannot be converted

Spent some time tracking down an annoying calling error:
```
Traceback (most recent call last):
File "i24ssx_Chip_Collect_py3v1.py", line 293, in create_dcid
dcid = conn.mx_acquisition.upsert_data_collection(list(dc_params.values()))
File ".../site-packages/ispyb/sp/acquisition.py", line 166, in upsert_data_collection
return self.get_connection().call_sp_write("upsert_dc", values)
File ".../site-packages/ispyb/connector/mysqlsp/main.py", line 88, in call_sp_write
result_args = cursor.callproc(procname=procname, args=args)
File ".../site-packages/mysql/connector/cursor_cext.py", line 466, in callproc
"Failed calling stored routine; {0}".format(err))
mysql.connector.errors.InterfaceError: Failed calling stored routine; Python type numpy.int64 cannot be converted
```
Calling API had provided a `numpy.int64` instead of an int. This looks like an int in `__str__` and `__repr__` so took an annoyingly long time to track down. I wonder if it'd be possible to tell which value caused this error, at least.