That line in the source code references the environment variable "Oracle_Home" - perhaps that has not been set.
From the Oracle-SQLLoader README:

You should have the following environment variables set:
  ORACLE_HOME   - the location of the Oracle installation
  ORACLE_SID    - the database instance name
  ORACLE_USERID - the username and password to connect to the database
+ as the format is username/password (e.g. scott/tiger)
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