Missing error location indication for bad MMSI

[mbof]

Repro steps: 1) Launch Edit as YAML (from a DAT or a device) 2) Paste the following config:

    - individual_directory:
        - Test: test 1234

3) Click Save

Observed:

• Error: MMSI number should have exactly 9 digits

Expected:

• Error: line (location), MMSI number should have exactly 9 digits (found "test 1234")