Add error handling docstrings.

borgmatic/hooks/data_source/dump.py

@@ -42,11 +42,13 @@ def write_data_source_dumps_metadata(borgmatic_runtime_directory, hook_name, dum
     borgmatic.actions.restore.Dump instances of dump metadata, write a metadata file describing all
     of those dumps. This metadata is being dumped so that it's available upon restore, e.g. to
     support the user selecting which data source(s) should be restored.
+
+    Raise ValueError if writing to the file results in an operating system error.
     '''
     dumps_metadata_path = os.path.join(borgmatic_runtime_directory, hook_name, 'dumps.json')
 
     try:
-        with open( dumps_metadata_path, 'w') as metadata_file:
+        with open(dumps_metadata_path, 'w') as metadata_file:
             json.dump([dump._asdict() for dump in dumps_metadata], metadata_file, sort_keys=True)
     except OSError as error:
         raise ValueError(f'Error writing to dumps metadata at {dumps_metadata_path}: {error}')
@@ -56,6 +58,9 @@ def parse_data_source_dumps_metadata(dumps_json, dumps_metadata_path):
     '''
     Given a dumps metadata JSON string as extracted from an archive, parse it into a tuple of
     borgmatic.actions.restore.Dump instances and return them.
+
+    Raise ValueError if parsing the JSON results in a JSON decode error or the data does not have
+    the expected keys.
     '''
     try:
         return tuple(borgmatic.actions.restore.Dump(**dump) for dump in json.loads(dumps_json))