fix: make sure zip stream buffer is always properly closed

rocrate/rocrate.py

@@ -482,23 +482,22 @@ def write_zip(self, out_path):
 
     def stream_zip(self):
         """ Create a stream of bytes representing the RO-Crate as a ZIP file. """
-        buffer = MemoryBuffer()
-        with zipfile.ZipFile(buffer, mode='w', compression=zipfile.ZIP_DEFLATED) as archive:
-            for writeable_entity in self.data_entities + self.default_entities:
-                current_file_path, current_out_file = None, None
-                for path, chunk in writeable_entity.stream():
-                    if path != current_file_path:
-                        if current_out_file:
-                            current_out_file.close()
-                        current_file_path = path
-                        current_out_file = archive.open(path, mode='w')
-                    current_out_file.write(chunk)
-                    yield buffer.read()
-                if current_out_file:
-                    current_out_file.close()
-
-        yield buffer.read()
-        buffer.close()
+        with MemoryBuffer() as buffer:
+            with zipfile.ZipFile(buffer, mode='w', compression=zipfile.ZIP_DEFLATED) as archive:
+                for writeable_entity in self.data_entities + self.default_entities:
+                    current_file_path, current_out_file = None, None
+                    for path, chunk in writeable_entity.stream():
+                        if path != current_file_path:
+                            if current_out_file:
+                                current_out_file.close()
+                            current_file_path = path
+                            current_out_file = archive.open(path, mode='w')
+                        current_out_file.write(chunk)
+                        yield buffer.read()
+                    if current_out_file:
+                        current_out_file.close()
+
+            yield buffer.read()
 
     def add_workflow(
             self, source=None, dest_path=None, fetch_remote=False, validate_url=False, properties=None,