Always strip preceding / from path in ManifestStore (#764)

* Always strip preceding / from path in ManifestStore

* Fix docs error

Author: maxrjones

docs/usage.md

@@ -403,7 +403,7 @@ repo = icechunk.Repository.open_or_create(storage)
 # you need to explicitly grant permissions to icechunk to read from the locations of your archival files
 config = icechunk.RepositoryConfig.default()
 config.set_virtual_chunk_container(
-    icechunk.VirtualChunkContainer("s3://my-bucket", icechunk.s3_store(region="us-east-1", anonymous=True)),
+    icechunk.VirtualChunkContainer("s3://my-bucket/", icechunk.s3_store(region="us-east-1", anonymous=True)),
 )
 
 # open a writable icechunk session to be able to add new contents to the store

virtualizarr/manifests/store.py

@@ -195,10 +195,11 @@ async def get(
         path_in_store = urlparse(path).path
         if hasattr(store, "prefix") and store.prefix:
             prefix = str(store.prefix).lstrip("/")
-            path_in_store = path_in_store.lstrip("/").removeprefix(prefix).lstrip("/")
         elif hasattr(store, "url"):
             prefix = urlparse(store.url).path.lstrip("/")
-            path_in_store = path_in_store.lstrip("/").removeprefix(prefix).lstrip("/")
+        else:
+            prefix = ""
+        path_in_store = path_in_store.lstrip("/").removeprefix(prefix).lstrip("/")
         # Transform the input byte range to account for the chunk location in the file
         chunk_end_exclusive = offset + length
         byte_range = _transform_byte_range(