fix(manager/nuget): skip invalid xml files (#16758)

lib/modules/manager/nuget/package-tree.spec.ts

@@ -155,12 +155,10 @@ describe('modules/manager/nuget/package-tree', () => {
       );
     });
 
-    it('throws error on invalid xml file', async () => {
+    it('skips on invalid xml file', async () => {
       git.getFileList.mockResolvedValue(['foo/bar.csproj']);
       Fixtures.mock({ '/tmp/repo/foo/bar.csproj': '<invalid' });
-      await expect(getDependentPackageFiles('foo/bar.csproj')).rejects.toThrow(
-        'Invalid xml file: foo/bar.csproj'
-      );
+      expect(await getDependentPackageFiles('foo/bar.csproj')).toEqual([]);
     });
   });
 });

lib/modules/manager/nuget/package-tree.ts

@@ -40,7 +40,7 @@ export async function getDependentPackageFiles(
   for (const f of packageFiles) {
     const doc = await readFileAsXmlDocument(f);
     if (!doc) {
-      throw new Error(`Invalid xml file: ${f}`);
+      continue;
     }
 
     const projectReferenceAttributes = doc