refactor: raise PipelineError when Pipeline.from_dict receives an invalid type (#8711)

* fix: error on invalid type

* add reno

* Update releasenotes/notes/fix-invalid-component-type-error-83ee00d820b63cc5.yaml

Co-authored-by: Stefano Fiorucci <stefanofiorucci@gmail.com>

* Update test/core/pipeline/test_pipeline.py

Co-authored-by: Stefano Fiorucci <stefanofiorucci@gmail.com>

* fix reno

* fix reno

* last reno fix

---------

Co-authored-by: Stefano Fiorucci <stefanofiorucci@gmail.com>

haystack/core/pipeline/base.py

@@ -167,8 +167,10 @@ class PipelineBase:
                                 f"Successfully imported module {module} but can't find it in the component registry."
                                 "This is unexpected and most likely a bug."
                             )
-                    except (ImportError, PipelineError) as e:
-                        raise PipelineError(f"Component '{component_data['type']}' not imported.") from e
+                    except (ImportError, PipelineError, ValueError) as e:
+                        raise PipelineError(
+                            f"Component '{component_data['type']}' (name: '{name}') not imported."
+                        ) from e
 
                 # Create a new one
                 component_class = component.registry[component_data["type"]]

releasenotes/notes/fix-invalid-component-type-error-83ee00d820b63cc5.yaml

@@ -0,0 +1,5 @@
+---
+enhancements:
+  - |
+    When `Pipeline.from_dict` receives an invalid type (e.g. empty string), an informative `PipelineError` is now
+    raised.

test/core/pipeline/test_pipeline.py

@@ -564,7 +564,7 @@ class TestPipeline:
         err.match("Missing 'type' in component 'add_two'")
 
     # UNIT
-    def test_from_dict_without_registered_component_type(self, request):
+    def test_from_dict_without_registered_component_type(self):
         data = {
             "metadata": {"test": "test"},
             "components": {"add_two": {"type": "foo.bar.baz", "init_parameters": {"add": 2}}},
@@ -575,6 +575,17 @@ class TestPipeline:
 
         err.match(r"Component .+ not imported.")
 
+    def test_from_dict_with_invalid_type(self):
+        data = {
+            "metadata": {"test": "test"},
+            "components": {"add_two": {"type": "", "init_parameters": {"add": 2}}},
+            "connections": [],
+        }
+        with pytest.raises(PipelineError) as err:
+            Pipeline.from_dict(data)
+
+        err.match(r"Component '' \(name: 'add_two'\) not imported.")
+
     # UNIT
     def test_from_dict_without_connection_sender(self):
         data = {"metadata": {"test": "test"}, "components": {}, "connections": [{"receiver": "some.receiver"}]}