RuntimeError: Failed to initialize graph

I'm following the guide in Getting Started document. After data conversion when I try running following command
>python -m tf_euler \
--data_dir ppi \
--max_id 56944 --feature_idx 1 --feature_dim 50 --label_idx 0 --label_dim 121 \
--model graphsage_supervised --mode train

I encounter error below
>Traceback (most recent call last):
File "/home/junhwan/anaconda3/lib/python3.7/runpy.py", line 193, in _run_module_as_main
"__main__", mod_spec)
File "/home/junhwan/anaconda3/lib/python3.7/runpy.py", line 85, in _run_code
exec(code, run_globals)
File "/home/junhwan/workspace/euler/tf_euler/__main__.py", line 28, in
tf.app.run(run_loop.main)
File "/home/junhwan/anaconda3/lib/python3.7/site-packages/tensorflow_core/python/platform/app.py", line 40, in run
_run(main=main, argv=argv, flags_parser=_parse_flags_tolerate_undef)
File "/home/junhwan/anaconda3/lib/python3.7/site-packages/absl/app.py", line 299, in run
_run_main(main, args)
File "/home/junhwan/anaconda3/lib/python3.7/site-packages/absl/app.py", line 250, in _run_main
sys.exit(main(argv))
File "/home/junhwan/workspace/euler/tf_euler/python/run_loop.py", line 405, in main
run_local(flags_obj, run_network_embedding)
File "/home/junhwan/workspace/euler/tf_euler/python/run_loop.py", line 366, in run_local
raise RuntimeError('Failed to initialize graph.')
RuntimeError: Failed to initialize graph.

It might be directory setting problem but I have ppi_data.dat file in euler/ppi directory. Any solutions? Thanks in advance

Start with tf_euler/python/run_loop.py at run_local, where the reported RuntimeError is raised, and trace the graph initialization path invoked by the supplied `python -m tf_euler` command. Check how `--data_dir ppi` is resolved relative to `ppi_data.dat`; done means the command initializes the graph without raising `RuntimeError: Failed to initialize graph.`

Written by the indexing model from the issue text.