Error creating engine to connect to the sql database!
Traceback (most recent call last):
  File "/app/app/data_pipeline.py", line 473, in run_pipeline
    engine = create_engine(os.getenv(connection_string_var))
  File "/usr/local/lib/python3.10/os.py", line 776, in getenv
    return environ.get(key, default)
  File "/usr/local/lib/python3.10/_collections_abc.py", line 824, in get
    return self[key]
  File "/usr/local/lib/python3.10/os.py", line 677, in __getitem__
    value = self._data[self.encodekey(key)]
  File "/usr/local/lib/python3.10/os.py", line 757, in encode
    raise TypeError("str expected, not %s" % type(value).__name__)
TypeError: str expected, not NoneType