Bug 34920: Ensure 'description' property is an empty string if 'lib' is null

Bug 34920: Ensure 'description' property is an empty string if 'lib' is null

Test plan:
1. Enable ERM module
2. Confirm that you can open the ERM module in the staff interface.
3. Go to the authorized values, select 'ERM_AGREEMENT_CLOSURE_REASON' and edit the 'Cancelled' authorized value by removing the description. Making this change with any of the ERM authorized values will result in an error.
4. Go back to the ERM module and notice that there is an error. 'Something went wrong: Error: Expected string - got null.'
5. Apply patch. Run yarn js:build. Repeat test plan
6. Create a new agreement. Pick status 'Closed'.
7. Open 'Closure reason'. Confirm there is an entry for 'Expired' and an empty entry below that.

Signed-off-by: Laura Escamilla <laura.escamilla@bywatersolutions.com>
Signed-off-by: Martin Renvoize <martin.renvoize@ptfs-europe.com>
Signed-off-by: Katrin Fischer <katrin.fischer@bsz-bw.de>