Adds error handler for registry errors

maven/lib/dependabot/maven/update_checker/version_finder.rb

@@ -203,8 +203,18 @@ def fetch_dependency_metadata(repository_details)
         rescue URI::InvalidURIError
           nil
         rescue Excon::Error::Socket, Excon::Error::Timeout,
-               Excon::Error::TooManyRedirects
-          raise if central_repo_urls.include?(repository_details["url"])
+               Excon::Error::TooManyRedirects => e
+
+          if central_repo_urls.include?(repository_details["url"])
+            response_status = response&.status || 0
+            response_body = if response
+                              "RegistryError: #{response.status} response status with body #{response.body}"
+                            else
+                              "Registry error: #{e.message}"
+                            end
+
+            raise RegistryError.new(response_status, response_body)
+          end
 
           nil
         end

maven/spec/dependabot/maven/update_checker/version_finder_spec.rb

@@ -524,6 +524,18 @@
       end
     end
 
+    context "with an invalid repository url specified" do
+      let(:dependency_files) { project_dependency_files("invalid_repository_url") }
+
+      before do
+        stub_request(:get, maven_central_metadata_url).to_raise(Excon::Error::Timeout)
+      end
+
+      it "raises a helpful error" do
+        expect { latest_version_details }.to raise_error(Dependabot::RegistryError)
+      end
+    end
+
     context "with a custom repository" do
       let(:pom_fixture_name) { "custom_repositories_pom.xml" }