**Steps to Reproduce**
1. Open file [Multi.zip](https://github.com/epam/Indigo/files/12866727/Multi.zip)
2. Press 'Save as...' button

**Actual behavior**
After clicking the 'Save as...' button, an error message appears: (array: invalid index -2 (size=0))

**Expected behavior**
File is saved without any errors.

**Screenshots**


Payload:
```
{
"struct": "{\n \"root\": {\n \"nodes\": [\n {\n \"$ref\": \"mol0\"\n },\n {\n \"$ref\": \"mol1\"\n },\n {\n \"type\": \"arrow\",\n \"data\": {\n \"mode\": \"open-angle\",\n \"pos\": [\n {\n \"x\": 12.204558219194714,\n \"y\": -7.925000000000001,\n \"z\": 0\n },\n {\n \"x\": 13.545441780805286,\n \"y\": -7.925000000000001,\n \"z\": 0\n }\n ]\n }\n }\n ]\n },\n \"mol0\": {\n \"type\": \"molecule\",\n \"atoms\": [\n {\n \"label\": \"C\",\n \"location\": [\n 4.066853757214407,\n -9.675006047591774,\n 0\n ]\n },\n {\n \"label\": \"C\",\n \"location\": [\n 4.9328759506707955,\n -10.175024583557567,\n 0\n ]\n },\n {\n \"label\": \"C\",\n \"location\": [\n 5.798898144127184,\n -9.675006047591774,\n 0\n ]\n },\n {\n \"label\": \"C\",\n \"location\": [\n 6.664919760835646,\n -10.175024583557567,\n 0\n ]\n },\n {\n \"label\": \"C\",\n \"location\": [\n 7.530942531039962,\n -9.675006047591774,\n 0\n ]\n },\n {\n \"label\": \"C\",\n \"location\": [\n 8.396964147748424,\n -10.175024583557567,\n 0\n ]\n },\n {\n \"label\": \"C\",\n \"location\": [\n 9.262985764456886,\n -9.675006047591774,\n 0\n ]\n },\n {\n \"label\": \"C\",\n \"location\": [\n 10.1290085346612,\n -10.175024583557567,\n 0\n ]\n },\n {\n \"label\": \"C\",\n \"location\": [\n 10.99503015136966,\n -9.675006047591774,\n 0\n ]\n },\n {\n \"label\": \"C\",\n \"location\": [\n 7.530942531039962,\n -8.674967822164326,\n 0\n ]\n },\n {\n \"label\": \"C\",\n \"location\": [\n 6.664919760835646,\n -8.174948709450604,\n 0\n ]\n },\n {\n \"label\": \"C\",\n \"location\": [\n 6.664919760835646,\n -7.175032177835677,\n 0\n ]\n },\n {\n \"label\": \"C\",\n \"location\": [\n 5.798898144127184,\n -6.675013065121953,\n 0\n ]\n },\n {\n \"label\": \"C\",\n \"location\": [\n 5.798898144127184,\n -5.674975416442434,\n 0\n ]\n },\n {\n \"label\": \"C\",\n \"location\": [\n 4.9328759506707955,\n -7.175032177835677,\n 0\n ]\n },\n {\n \"label\": \"C\",\n \"location\": [\n 4.9328759506707955,\n -8.174948709450604,\n 0\n ]\n },\n {\n \"label\": \"C\",\n \"location\": [\n 4.066853757214407,\n -6.675013065121953,\n 0\n ]\n },\n {\n \"label\": \"C\",\n \"location\": [\n 3.200831563758019,\n -7.175032177835677,\n 0\n ]\n },\n {\n \"label\": \"C\",\n \"location\": [\n 2.334809370301631,\n -6.675013065121953,\n 0\n ]\n }\n ],\n \"bonds\": [\n {\n \"type\": 1,\n \"atoms\": [\n 0,\n 1\n ]\n },\n {\n \"type\": 1,\n \"atoms\": [\n 2,\n 3\n ]\n },\n {\n \"type\": 1,\n \"atoms\": [\n 3,\n 4\n ]\n },\n {\n \"type\": 1,\n \"atoms\": [\n 4,\n 5\n ]\n },\n {\n \"type\": 1,\n \"atoms\": [\n 5,\n 6\n ]\n },\n {\n \"type\": 1,\n \"atoms\": [\n 6,\n 7\n ]\n },\n {\n \"type\": 1,\n \"atoms\": [\n 7,\n 8\n ]\n },\n {\n \"type\": 1,\n \"atoms\": [\n 4,\n 9\n ]\n },\n {\n \"type\": 1,\n \"atoms\": [\n 9,\n 10\n ]\n },\n {\n \"type\": 1,\n \"atoms\": [\n 10,\n 11\n ]\n },\n {\n \"type\": 1,\n \"atoms\": [\n 11,\n 12\n ]\n },\n {\n \"type\": 1,\n \"atoms\": [\n 12,\n 13\n ]\n },\n {\n \"type\": 1,\n \"atoms\": [\n 12,\n 14\n ]\n },\n {\n \"type\": 1,\n \"atoms\": [\n 14,\n 15\n ]\n },\n {\n \"type\": 1,\n \"atoms\": [\n 14,\n 16\n ]\n },\n {\n \"type\": 1,\n \"atoms\": [\n 16,\n 17\n ]\n },\n {\n \"type\": 1,\n \"atoms\": [\n 17,\n 18\n ]\n },\n {\n \"type\": 1,\n \"atoms\": [\n 2,\n 1\n ]\n }\n ],\n \"sgroups\": [\n {\n \"type\": \"SRU\",\n \"atoms\": [\n 4,\n 10,\n 9,\n 11,\n 12,\n 13,\n 14,\n 15,\n 16,\n 17,\n 18\n ],\n \"subscript\": \"n\",\n \"connectivity\": \"HT\"\n },\n {\n \"type\": \"MUL\",\n \"atoms\": [\n 3,\n 2,\n 4,\n 5,\n 6,\n 10,\n 9,\n 11,\n 12,\n 13,\n 14,\n 15,\n 16,\n 17,\n 18\n ],\n \"mul\": 3\n },\n {\n \"type\": \"SRU\",\n \"atoms\": [\n 14,\n 12,\n 13,\n 15,\n 16\n ],\n \"subscript\": \"n\",\n \"connectivity\": \"HT\"\n }\n ]\n },\n \"mol1\": {\n \"type\": \"molecule\",\n \"atoms\": [\n {\n \"label\": \"C\",\n \"location\": [\n 16.487014235543114,\n -9.675006047591774,\n 0\n ]\n },\n {\n \"label\": \"C\",\n \"location\": [\n 17.35303469875572,\n -10.175024583557567,\n 0\n ]\n },\n {\n \"label\": \"C\",\n \"location\": [\n 18.21905862245589,\n -9.675006047591774,\n 0\n ]\n },\n {\n \"label\": \"C\",\n \"location\": [\n 19.085080239164355,\n -10.175024583557567,\n 0\n ]\n },\n {\n \"label\": \"C\",\n \"location\": [\n 19.95110185587282,\n -9.675006047591774,\n 0\n ]\n },\n {\n \"label\": \"C\",\n \"location\": [\n 20.81712347258128,\n -10.175024583557567,\n 0\n ]\n },\n {\n \"label\": \"C\",\n \"location\": [\n 21.68314739628145,\n -9.675006047591774,\n 0\n ]\n },\n {\n \"label\": \"C\",\n \"location\": [\n 22.549169012989907,\n -10.175024583557567,\n 0\n ]\n },\n {\n \"label\": \"C\",\n \"location\": [\n 23.415190629698373,\n -9.675006047591774,\n 0\n ]\n },\n {\n \"label\": \"C\",\n \"location\": [\n 19.95110185587282,\n -8.674967822164326,\n 0\n ]\n },\n {\n \"label\": \"C\",\n \"location\": [\n 19.085080239164355,\n -8.174948709450604,\n 0\n ]\n },\n {\n \"label\": \"C\",\n \"location\": [\n 19.085080239164355,\n -7.175032177835677,\n 0\n ]\n },\n {\n \"label\": \"C\",\n \"location\": [\n 18.21905862245589,\n -6.675013065121953,\n 0\n ]\n },\n {\n \"label\": \"C\",\n \"location\": [\n 18.21905862245589,\n -5.674975416442434,\n 0\n ]\n },\n {\n \"label\": \"C\",\n \"location\": [\n 17.35303469875572,\n -7.175032177835677,\n 0\n ]\n },\n {\n \"label\": \"C\",\n \"location\": [\n 17.35303469875572,\n -8.174948709450604,\n 0\n ]\n },\n {\n \"label\": \"C\",\n \"location\": [\n 16.487014235543114,\n -6.675013065121953,\n 0\n ]\n },\n {\n \"label\": \"C\",\n \"location\": [\n 15.620991465338799,\n -7.175032177835677,\n 0\n ]\n },\n {\n \"label\": \"C\",\n \"location\": [\n 14.75496984863034,\n -6.675013065121953,\n 0\n ]\n }\n ],\n \"bonds\": [\n {\n \"type\": 1,\n \"atoms\": [\n 6,\n 7\n ]\n },\n {\n \"type\": 1,\n \"atoms\": [\n 0,\n 1\n ]\n },\n {\n \"type\": 1,\n \"atoms\": [\n 2,\n 1\n ]\n },\n {\n \"type\": 1,\n \"atoms\": [\n 2,\n 3\n ]\n },\n {\n \"type\": 1,\n \"atoms\": [\n 3,\n 4\n ]\n },\n {\n \"type\": 1,\n \"atoms\": [\n 4,\n 5\n ]\n },\n {\n \"type\": 1,\n \"atoms\": [\n 5,\n 6\n ]\n },\n {\n \"type\": 1,\n \"atoms\": [\n 7,\n 8\n ]\n },\n {\n \"type\": 1,\n \"atoms\": [\n 4,\n 9\n ]\n },\n {\n \"type\": 1,\n \"atoms\": [\n 9,\n 10\n ]\n },\n {\n \"type\": 1,\n \"atoms\": [\n 10,\n 11\n ]\n },\n {\n \"type\": 1,\n \"atoms\": [\n 11,\n 12\n ]\n },\n {\n \"type\": 1,\n \"atoms\": [\n 12,\n 13\n ]\n },\n {\n \"type\": 1,\n \"atoms\": [\n 12,\n 14\n ]\n },\n {\n \"type\": 1,\n \"atoms\": [\n 14,\n 15\n ]\n },\n {\n \"type\": 1,\n \"atoms\": [\n 14,\n 16\n ]\n },\n {\n \"type\": 1,\n \"atoms\": [\n 16,\n 17\n ]\n },\n {\n \"type\": 1,\n \"atoms\": [\n 17,\n 18\n ]\n }\n ],\n \"sgroups\": [\n {\n \"type\": \"SRU\",\n \"atoms\": [\n 16,\n 12,\n 14,\n 15,\n 13\n ],\n \"subscript\": \"n\",\n \"connectivity\": \"HT\"\n },\n {\n \"type\": \"MUL\",\n \"atoms\": [\n 6,\n 2,\n 5,\n 4,\n 3,\n 9,\n 10,\n 11,\n 12,\n 13,\n 14,\n 15,\n 16,\n 17,\n 18\n ],\n \"mul\": 3\n },\n {\n \"type\": \"SRU\",\n \"atoms\": [\n 4,\n 9,\n 10,\n 11,\n 12,\n 13,\n 14,\n 15,\n 16,\n 17,\n 18\n ],\n \"subscript\": \"n\",\n \"connectivity\": \"HT\"\n },\n {\n \"type\": \"DAT\",\n \"atoms\": [\n 13\n ],\n \"fieldName\": \"\",\n \"fieldData\": \"Cl-Br\"\n },\n {\n \"type\": \"GEN\",\n \"atoms\": [\n 2,\n 1,\n 3,\n 4,\n 5,\n 6,\n 7,\n 9,\n 10,\n 11,\n 12,\n 13,\n 14,\n 15,\n 16,\n 17,\n 18\n ]\n },\n {\n \"type\": \"DAT\",\n \"atoms\": [\n 1,\n 2,\n 3,\n 4,\n 5,\n 6,\n 7\n ],\n \"fieldName\": \"\",\n \"fieldData\": \"C\",\n \"bonds\": [\n 0,\n 2,\n 3,\n 4,\n 5,\n 6\n ]\n }\n ]\n }\n}",
"output_format": "chemical/x-mdl-rxnfile",
"options": {
"smart-layout": true,
"ignore-stereochemistry-errors": true,
"mass-skip-error-on-pseudoatoms": false,
"gross-formula-add-rsites": true,
"aromatize-skip-superatoms": true,
"dearomatize-on-load": false,
"ignore-no-chiral-flag": false,
"gross-formula-add-isotopes": true
}
}
```
Responce:
```

The page is temporarily unavailable


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nginx error!

The page you are looking for is temporarily unavailable. Please try again later.

Website Administrator

Something has triggered an error on your
website. This is the default error page for
nginx that is distributed with
Amazon Linux 2. It is located
/usr/share/nginx/html/50x.html

You should customize this error page for your own
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```
**Desktop (please complete the following information):**
- OS: Windows 10
- Browser Chrome
- Version 112.0.5615.138 (Official Build) (64-bit)

**Indigor version**
[Version 1.14.0-rc.6](https://lifescience.opensource.epam.com/ketcher/index.html)