The error occurs as you have a CTI provider installed on the agent pc that is not compatible with the current version of CS you are trying to run.
Either remove the provider or get it updated and the issue will be resolved.
JS Error in full:
Error: Object doesn't support property or method 'StartManualScript'
Article ID: 603, Created: December 18, 2013 at 5:34 PM, Modified: June 14, 2016 at 4:33 PM