Macro: it is possible to add CHEMs without R1/R2 to the backbone chain in sequence mode

[Zhirnoff]

Case1 Steps to Reproduce

1. Add a structure in micro mode.
2. Switch to macro -> sequence view -> edit mode (e.g., starting a new sequence).
3. Enter monomers on same line as chemical icon.
4. Switch to flex/snake mode.

Actual behavior After editing in sequence mode, structures have connections that should not be formed because they do not have attachment points

Expected behavior No connection should be established in Flex mode. In sequence mode - it should be 2 sequences

Screenshots

https://github.com/epam/ketcher/assets/62464241/c760f50e-7734-4a10-9730-864b88a11e11

Case2 Steps to Reproduce

1. Add a CHEM in macro mode with 1 attachment point.(e.g. MCC)
2. Switch to sequence view -> edit mode (e.g., edit sequence).
3. Enter monomers on same line as chemical icon.
4. Switch to flex/snake mode.

Actual behavior After editing in sequence mode, structures have connections that should not be formed because they do not have R2 attachment point and connection occurs through non-existent one

Expected behavior After editing in sequence mode, structures do not have connections because they do not have attachment points for connection through R2-R1.

Screenshots

https://github.com/epam/ketcher/assets/62464241/ed85c074-a83e-4a24-9b17-05f1da4351b3

Desktop (please complete the following information):

• OS: Windows 11
• Browser Chrome
• Version 112.0.5615.138 (Official Build) (64-bit)

Ketcher version [Version 2.20.0-rc.1]

[vanoprenko]

Please elaborate and specify the details of expected behavior

[AlexeyGirin]

Moved to Refined Backlog since not fixed over 1 release

[NadezhdaPeskun]

Should be fixed with (4708, 4575, 4506,4706) Ketcher issues Error message should be added: Error Message: It is impossible to merge fragments. Attachment point to establish bonds are not available.