`utils.__from_nx_to_igraph` breaks when isolated nodes are present

[bgleaso1]

Describe the bug

Conversion from nx.Graph to ig.Graph in utils.__from_nx_to_igraph breaks when there are isolates (nodes without edges) present. It throws the following error:

networkx.exception.AmbiguousSolution: Disconnected graph: Ambiguous solution for bipartite sets.

To Reproduce

Steps to reproduce the behavior:

import cdlib
import networkx as nx
from cdlib import utils

_g = nx.Graph({
    '5013469205': {},
    '5012920363': {'5012920217': {}},
    '5012920217': {'5012920363': {}},
    '5012920377': {'5013279789': {}},
    '5012920753': {'5013279789': {}},
    '5013279789': {'5012920377': {}, '5012920753': {}},
    '1001352506': {'5001229487': {}},
    '5001229487': {'1001352506': {}}
})
utils.__from_nx_to_igraph(_g)

• CDlib version 0.3.0

• Operating System macOS Monterey 12.5.1

• Python version 3.11.0

• Version(s) of CDlib required libraries angelcommunity == 2.0.0 demon == 2.0.6 dynetx == 0.3.2 eva-lcd == 0.1.1 markov-clustering == 0.0.6.dev0 matplotlib == 3.8.1 networkx == 3.1 nf1 == 0.0.4 numpy == 1.25.2 pandas == 2.1.1 pooch == 1.8.0 pulp == 2.7.0 python-igraph == 0.10.8 python-levenshtein == 0.23.0 python-louvain == 0.16 scikit-learn == 1.3.2 scipy == 1.11.3 seaborn == 0.13.0 thresholdclustering == 1.1 tqdm == 4.66.1

Expected behavior Conversion to igraph.Graph should succeed, error free.