Fix linting and static typing errors

Author: ctrueden

src/pombast/cache/_repo.py

@@ -6,7 +6,13 @@
 from pathlib import Path
 from typing import TYPE_CHECKING
 
-from pombast.util._git import bare_clone, default_branch, fetch_tags, has_ref, remote_url
+from pombast.util._git import (
+    bare_clone,
+    default_branch,
+    fetch_tags,
+    has_ref,
+    remote_url,
+)
 
 if TYPE_CHECKING:
     from pombast.core._component import Component

src/pombast/core/_pipeline.py

@@ -251,6 +251,16 @@ def run(self) -> ValidationReport:
                     )
                     shutil.rmtree(source_dir)
                 try:
+                    if component.scm_url is None:
+                        _log.error("%s: no scm url — %s", component.coordinate)
+                        report.results.append(
+                            BuildResult(
+                                component=component,
+                                status=BuildStatus.ERROR,
+                                skipped_reason="no scm url",
+                            )
+                        )
+                        continue
                     bare_repo = repo_cache.ensure_ref(component, component.scm_url, tag)
                     shallow_clone(bare_repo, tag, source_dir)
                 except Exception as e: