Fix export_sources for non-existent recipes in a local index (#16776)

* Fix export_sources for non-existent recipes in a local index.

Previously, a local recipe index client would raise a different
exception than a REST client when exporting sources for a non-
existent recipe, which causes a hard failure rather than allowing
the caller to move on to the next remote. This patch makes their
behaviours consistent and raise a RecipeNotFoundException instead.

* Fix formatting

* refactored test

* use try-except

---------

Co-authored-by: memsharded <james@conan.io>

conans/client/rest_client_local_recipe_index.py

@@ -11,7 +11,8 @@
 from conan.internal.cache.home_paths import HomePaths
 from conans.client.cmd.export import cmd_export
 from conans.client.loader import ConanFileLoader
-from conans.errors import ConanException, PackageNotFoundException, RecipeNotFoundException
+from conans.errors import ConanException, PackageNotFoundException, RecipeNotFoundException, \
+    ConanReferenceDoesNotExistInDB, NotFoundException
 from conans.model.conf import ConfDefinition
 from conans.model.recipe_ref import RecipeReference
 from conans.util.files import load, save, rmdir, copytree_compat
@@ -76,7 +77,12 @@ def get_recipe(self, ref, dest_folder):
         return self._copy_files(export_folder, dest_folder)
 
     def get_recipe_sources(self, ref, dest_folder):
-        export_sources = self._app.cache.recipe_layout(ref).export_sources()
+        try:
+            export_sources = self._app.cache.recipe_layout(ref).export_sources()
+        except ConanReferenceDoesNotExistInDB as e:
+            # This can happen when there a local-recipes-index is being queried for sources it
+            # doesn't contain
+            raise NotFoundException(str(e))
         return self._copy_files(export_sources, dest_folder)
 
     def get_package(self, pref, dest_folder, metadata, only_metadata):

test/functional/test_local_recipes_index.py

@@ -118,3 +118,35 @@ def package_info(self):
         # Finally lets remove the remote, check that the clone is cleared
         c.run('remote remove local')
         assert "Removing temporary files for 'local' local-recipes-index remote" in c.out
+
+    def test_not_found(self):
+        """testing that the correct exception is raised when a recipe is not found
+        """
+        repo1_folder = temp_folder()
+        repo2_folder = temp_folder()
+        config_yml = textwrap.dedent("""\
+            versions:
+              "0.1":
+                folder: all
+            """)
+        conanfile = textwrap.dedent("""\
+            import os
+            from conan import ConanFile
+            from conan.tools.files import copy
+
+            class PkgRecipe(ConanFile):
+                name = "pkg"
+
+                def export_sources(self):
+                    copy(self, "*", src=self.recipe_folder, dst=self.export_sources_folder)
+            """)
+
+        save_files(repo2_folder, {"recipes/pkg/config.yml": config_yml,
+                                  "recipes/pkg/all/conanfile.py": conanfile,
+                                  "recipes/pkg/all/pkg.h": gen_function_h(name="pkg")})
+
+        c = TestClient()
+        c.run(f"remote add local1 '{repo1_folder}'")
+        c.run(f"remote add local2 '{repo2_folder}'")
+        c.run("install --requires=pkg/0.1 --build=missing")
+        assert "Install finished successfully" in c.out