AssertionError: NeighborSampler doesn't support mutable graphs. Please turn it into an immutable graph with DGLGraphStale.readonly

[HandsomeEffortMonster]

DGLGraph now always supports mutable operations like add_nodes and add_edges.
return warnings.warn(message, category=category, stacklevel=1)
Traceback (most recent call last):
File "/tmp/pycharm_project_609/KPGNN/main.py", line 139, in
train_indices, indices_to_remove, model = KPGNN.initial_maintain(train_i, 0, data_split, metrics,
File "/tmp/pycharm_project_609/KPGNN/model.py", line 420, in initial_maintain
for batch_id, nf in enumerate(dgl.contrib.sampling.NeighborSampler(g,
File "/home/x/miniconda3/envs/python39/lib/python3.9/site-packages/dgl/contrib/sampling/sampler.py", line 320, in init
assert g.is_readonly, "NeighborSampler doesn't support mutable graphs. " +
AssertionError: NeighborSampler doesn't support mutable graphs. Please turn it into an immutable graph with DGLGraphStale.readonly
ERROR conda.cli.main_run:execute(125): conda run python /tmp/pycharm_project_609/KPGNN/main.py failed. (See above for error)