Ketcher creates invalid molfiles with "NaN"

[evgeniiFrolov1]

Draw the structure shown below in Ketcher. If you export it as a molfile directly from Ketcher you will see the molfile contains some "NaN" values, and you get an error if you click the "use this structure" button.

Steps to Reproduce

1. Go to ketcher_standalone or ketcher_remote
2. Click on Custom Templates
3. Click on Functional Groups
4. Choose PhCOOH
5. Click on abriviation
6. Click on Charge Minus (5)
7. Click on OH
8. Add Na to the canvas
9. Click on Charge Plus (5)
10. Click on Na
11. Click on Save
12. Choose MDL Molfile V2000

Expected behavior
Preview does not contain NaN

Actual behavior
Preview contains NaN

Screenshots

Ketcher version [e.g. v2.4.2-115-gcf0c1394].
Ketcher v2.5.2

Additional context
Add any other context about the problem here.