JOE should show correct comboboxes for next state and error state when editing a job chain

Current Situation

• When inserting a new job chain node the comboboxes for next state and error state are empty,
• When editing a job chain node the comboboxes for next state and error state are showing different content.
• When inserting a node and clicking the node entry after inserting, an error message appears
• The comboxboxes do not have a default for the success and the error node.
• When creating a new node, the combobox for the next state is empty
• When creating a new node, the combobox for the error state lists the first node, the first error node and then all other nodes.

Desired Behaviour

• When inserting a new job chain node the comboboxes for next state and error state should be filled with the actual available states, except the state of the actual node.
• When editing a job chain node the comboboxes for next state and error state should have the same content.
• When inserting a node and clicking the node entry after inserting, no error message should appear.
• The comboxboxes should have a default for the success and the error node.
• When creating a new node, the combobox for the next state should contain all states + the default node names for error and success.
• When creating a new node, the combobox for the error state should contain all states + the default node names for error and success.