Antisense creating doesn't work if ambiguous CHEM present in the chain selection

[AlexeyGirin]

Steps to Reproduce

1. Go to Macro - Snake mode
2. Load from HELM using paste from clipboard: CHEM1{([4aPEGMal],[4FB],[MCC],[sDBL])}|RNA1{R(A)P}$RNA1,CHEM1,3:R2-1:R1$$$V2.0
3. Select all monomers on the canvas and click Create Antisense Strand from context menu

Actual behavior
Nothing happens
Error in console:

Expected behavior
Antisense chain created

As per requirement:

1.3. If multiple chains are selected and more than one satisfies the previous requirements, the "Create Antisense Strand" option should appear, and if clicked, multiple antisense chains are created.

Versions

• Ketcher Version 2.28.0-rc.1 Build at 2024-12-03; 17:04:52
• Indigo Version 1.27.0-rc.1.0-g8d656a341-wasm32-wasm-clang-19.0.0
• Chrome Version 131.0.6778.109 (Official Build) (64-bit)
• Win10

Issue found while testing - #5678