Salesforce returns well formatted JSON error responses requests to the Salesforce REST API can not be fulfilled or encounter errors.
The Salesforce Connector should properly parse any JSON error responses received from Salesforce and set appropriate messages within ConnectorExceptions which are thrown.
For example, the current connector implementation writes raw JSON error response as String values within the resulting ConnectorException. These string values are not easily parsed by a UI making it difficult to present friendly error messages to users.
Example ConnectorException message:
What is most relevant and what should be set within ConnectorException's is the message attribute within the JSON error response