Avoid giving 500 errors when corpus_id is not set

Closes #170 (closed)

arkindex_worker/worker/base.py

@@ -193,6 +193,10 @@ class BaseWorker(object):
 
         # Define corpus_id from environment
         self.corpus_id = os.environ.get("ARKINDEX_CORPUS_ID")
+        if not self.corpus_id:
+            logger.warning(
+                "'ARKINDEX_CORPUS_ID' was not set in the environment. Any API request involving a `corpus_id` will fail."
+            )
 
         # Load all required secrets
         self.secrets = {name: self.load_secret(name) for name in required_secrets}