Ensure that config build fails on unit collection errors

ampel/config/collector/UnitConfigCollector.py

@@ -73,6 +73,7 @@ def add(self, # type: ignore[override]
 								)
 						except Exception:
 							self.logger.info(f'Units auto-registration has failed for package {el}')
+							self.has_error = True
 						continue
 
 					# Standart unit definition (ex: ampel.t3.stage.T3AggregatingStager)
@@ -138,6 +139,8 @@ def add(self, # type: ignore[override]
 					exc_info=e
 				)
 
+				self.has_error = True
+
 		if isinstance(self.logger.handlers[0], AggregatingLoggingHandlerProtocol):
 			self.logger.handlers[0].aggregate_interval = agg_int
 
@@ -172,6 +175,7 @@ def get_mro(self, module_fqn: str, class_name: str) -> None | tuple[int, list[st
 		except Exception as e:
 
 			self.err_fqns.append((module_fqn, e))
+			self.has_error = True
 
 			if self.options.hide_module_not_found_errors and isinstance(e, ModuleNotFoundError):
 				return None

ampel/test/test_config.py

@@ -8,11 +8,14 @@
 import pytest
 import yaml
 from pydantic import ValidationError
+from pytest_mock import MockerFixture
 
 from ampel.abstract.AbsEventUnit import AbsEventUnit
 from ampel.base.BadConfig import BadConfig
 from ampel.config.builder.ConfigChecker import ConfigChecker
 from ampel.config.builder.ConfigValidator import ConfigValidator
+from ampel.config.builder.DisplayOptions import DisplayOptions
+from ampel.config.builder.DistConfigBuilder import DistConfigBuilder
 from ampel.core.UnitLoader import UnitLoader
 from ampel.test.test_JobCommand import run
 from ampel.util.mappings import set_by_path
@@ -146,3 +149,18 @@ def test_validate_config(testing_config, tmpdir, patch, result):
             )
             == result
         )
+
+def test_collect_bad_unit(tmp_path: Path, mocker: MockerFixture) -> None:
+    cb = DistConfigBuilder(DisplayOptions(verbose=True, debug=True))
+
+    bad_unit_config = tmp_path / "unit.yaml"
+    with bad_unit_config.open("w") as f:
+        yaml.dump(["flerhherher.Floop"], f)
+
+    mocker.patch("ampel.config.builder.DistConfigBuilder.get_files", return_value=[str(bad_unit_config)])
+
+    cb.load_distributions()
+    assert cb.first_pass_config.has_nested_error()
+
+    with pytest.raises(ValueError):
+        cb.build_config(stop_on_errors=2)