getSequence should not give a response to the preservation of nucleotide compounds with other monomers

**Steps to Reproduce**
1. Open Macromolecules mode - Flex mode
2. Open Console
3. Add schema from file [Schema nucleotide with chem with different connections.ket.zip](https://github.com/user-attachments/files/16266559/Schema.nucleotide.with.chem.with.different.connections.ket.zip)
4. Type in the Console `ketcher.getSequence()`

**Expected behavior**
An error should be displayed

**Actual behavior**
A response with the code is displayed

The issue is the same for these files:
[Schema nucleotide with base with different connections.ket.zip](https://github.com/user-attachments/files/16266876/Schema.nucleotide.with.base.with.different.connections.ket.zip)
[Schema nucleotide with peptide with different connections.ket.zip](https://github.com/user-attachments/files/16266877/Schema.nucleotide.with.peptide.with.different.connections.ket.zip)
[Schema nucleotides with phosphate with different connections.ket.zip](https://github.com/user-attachments/files/16266878/Schema.nucleotides.with.phosphate.with.different.connections.ket.zip)
[Schema nucleotide with sugar with different connections.ket.zip](https://github.com/user-attachments/files/16266879/Schema.nucleotide.with.sugar.with.different.connections.ket.zip)

**Environment details:**
Ketcher Version 2.23.0-rc.2 Build at 2024-07-10; 19:39:22
Indigo Version 1.22.0-rc.2.0-ga21fb5d8f-wasm32-wasm-clang-19.0.0
Chrome Версия 126.0.6478.127 (Официальная сборка), (arm64)
MacOs Sonoma 14.5
Issue found for https://github.com/epam/ketcher/issues/4382