Handle Bundler::Fetcher::NetworkDownError during Bundler setup

We occasionally receive reports of `Bundler::Fetcher::NetworkDownError`s happening
in our telemetry. We expect errors like this occasionally and seeing them in
telemetry does not really help us. For now, we can handle these errors so they
don't get written to our error logging file.

Author: egiurleo

lib/ruby_lsp/setup_bundler.rb

@@ -234,13 +234,14 @@ def run_bundle_install(bundle_gemfile = @gemfile)
         # If no error occurred, then clear previous errors
         @error_path.delete if @error_path.exist?
         $stderr.puts("Ruby LSP> Composed bundle installation complete")
-      rescue Errno::EPIPE
-        # If the $stderr pipe was closed by the client, for example when closing the editor during running bundle
-        # install, we don't want to write the error to a file or else we will report to telemetry on the next launch and
-        # it does not represent an actual error.
+      rescue Errno::EPIPE, Bundler::Fetcher::NetworkDownError
+        # There are cases where we expect certain errors to happen occasionally, and we don't want to write them to
+        # a file, which would report to telemetry on the next launch.
         #
-        # This situation may happen because while running bundle install, the server is not yet ready to receive
-        # shutdown requests and we may continue doing work until the process is killed.
+        # - The $stderr pipe might be closed by the client, for example when closing the editor during running bundle
+        # install. This situation may happen because, while running bundle install, the server is not yet ready to
+        # receive shutdown requests and we may continue doing work until the process is killed.
+        # - Bundler might also encounter a network error.
         @error_path.delete if @error_path.exist?
       rescue => e
         # Write the error object to a file so that we can read it from the parent process

test/setup_bundler_test.rb

@@ -914,6 +914,27 @@ def test_ignores_bundle_package
     end
   end
 
+  def test_handles_network_down_error_during_bundle_install
+    Dir.mktmpdir do |dir|
+      Dir.chdir(dir) do
+        File.write(File.join(dir, "gems.rb"), <<~GEMFILE)
+          source "https://rubygems.org"
+          gem "irb"
+        GEMFILE
+
+        Bundler.with_unbundled_env do
+          system("bundle install")
+
+          compose = RubyLsp::SetupBundler.new(dir, launcher: true)
+          compose.expects(:bundle_check).raises(Bundler::Fetcher::NetworkDownError)
+          compose.setup!
+
+          refute_path_exists(File.join(dir, ".ruby-lsp", "install_error"))
+        end
+      end
+    end
+  end
+
   def test_is_resilient_to_pipe_being_closed_by_client_during_compose
     Dir.mktmpdir do |dir|
       Dir.chdir(dir) do