Fix iterating over manifest (#3792)

* Fix

* Update CHANGELOG

Co-authored-by: Nikita Manovich <nikita.manovich@intel.com>

CHANGELOG.md

@@ -37,6 +37,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - Exception `DataCloneError: The object could not be cloned` (<https://github.com/openvinotoolkit/cvat/pull/3733>)
 - Fixed extension comparison in task frames CLI (<https://github.com/openvinotoolkit/cvat/pull/3674>)
 - Incorrect work when copy job list with "Copy" button (<https://github.com/openvinotoolkit/cvat/pull/3749>)
+- Iterating over manifest (<https://github.com/openvinotoolkit/cvat/pull/3792>)
 - Manifest removing (<https://github.com/openvinotoolkit/cvat/pull/3791>)
 
 ### Security

utils/dataset_manifest/core.py

@@ -396,12 +396,11 @@ class _ManifestManager(ABC):
             image_number = 0
             line = manifest_file.readline()
             while line:
-                if not line.strip():
-                    continue
-                parsed_properties = json.loads(line)
-                self._json_item_is_valid(**parsed_properties)
-                yield (image_number, parsed_properties)
-                image_number += 1
+                if line.strip():
+                    parsed_properties = json.loads(line)
+                    self._json_item_is_valid(**parsed_properties)
+                    yield (image_number, parsed_properties)
+                    image_number += 1
                 line = manifest_file.readline()
 
     @property