fix: make pypdf converter more robust (#8427)

* fix: make `from_dict` of `PyPDFToDocument` more robust

* chore: drop trailing space

* converting method to static and making the comment shorter

* reverting method to static

---------

Co-authored-by: David S. Batista <[email protected]>

Author: wochinge

Diff for: haystack/components/converters/pypdf.py

@@ -108,8 +108,10 @@ def from_dict(cls, data):
         :returns:
             Deserialized component.
         """
-        converter_class = deserialize_type(data["init_parameters"]["converter"]["type"])
-        data["init_parameters"]["converter"] = converter_class.from_dict(data["init_parameters"]["converter"])
+        # the converter default is `None`, check if it was defined before deserializing
+        if "converter" in data["init_parameters"]:
+            converter_class = deserialize_type(data["init_parameters"]["converter"]["type"])
+            data["init_parameters"]["converter"] = converter_class.from_dict(data["init_parameters"]["converter"])
         return default_from_dict(cls, data)
 
     @component.output_types(documents=List[Document])

Diff for: releasenotes/notes/pypdf-converter-robust-from-dict-35ebe6aaab944b19.yaml

@@ -0,0 +1,5 @@
+---
+fixes:
+  - |
+    Make the `from_dict` method of the `PyPDFToDocument` more robust to cases when the converter is
+    not provided in the dictionary.

Diff for: test/components/converters/test_pypdf_to_document.py

@@ -40,6 +40,12 @@ def test_from_dict(self):
         assert isinstance(instance, PyPDFToDocument)
         assert isinstance(instance.converter, DefaultConverter)
 
+    def test_from_dict_no_converter(self):
+        data = {"type": "haystack.components.converters.pypdf.PyPDFToDocument", "init_parameters": {}}
+        instance = PyPDFToDocument.from_dict(data)
+        assert isinstance(instance, PyPDFToDocument)
+        assert isinstance(instance.converter, DefaultConverter)
+
     @pytest.mark.integration
     def test_run(self, test_files_path, pypdf_converter):
         """