OPI not working with FFs

[cplett]

Describe the bug
When using a force field such as GFN-FF, no output can be read. The JSON-gbw is not written and the JSON-property file is empty.

To Reproduce
Perform a simple GFN-FF calculation and try to parse the output. The result will be a FileNotFound error as the JSON-gbw file is not written.

Version:

• ORCA 6.1.0

Additional context
Even when JSON-gbw parsing is disabled (as discussed in issue #18), results remain inaccessible due to the empty JSON-property file. Probably, changes of the ORCA code are necessary.