Handle when server info doesn't have the storage in question

lib/gitlab/gitaly_client.rb

@@ -406,7 +406,8 @@ module Gitlab
     def self.filesystem_id(storage)
       response = Gitlab::GitalyClient::ServerService.new(storage).info
       storage_status = response.storage_statuses.find { |status| status.storage_name == storage }
-      storage_status.filesystem_id
+
+      storage_status&.filesystem_id
     end
 
     def self.filesystem_id_from_disk(storage)

spec/lib/gitlab/gitaly_client_spec.rb

@@ -27,6 +27,16 @@ describe Gitlab::GitalyClient do
     end
   end
 
+  describe '.filesystem_id' do
+    it 'returns an empty string when the storage is not found in the response' do
+      response = double("response")
+      allow(response).to receive(:storage_statuses).and_return([])
+      allow_any_instance_of(Gitlab::GitalyClient::ServerService).to receive(:info).and_return(response)
+
+      expect(described_class.filesystem_id('default')).to eq(nil)
+    end
+  end
+
   describe '.stub_class' do
     it 'returns the gRPC health check stub' do
       expect(described_class.stub_class(:health_check)).to eq(::Grpc::Health::V1::Health::Stub)