better error handling for Import.

lib/trailblazer/pro/editor/import.rb

@@ -2,8 +2,10 @@ module Trailblazer
   module Pro
     module Editor
       class Import < Trailblazer::Activity::Railway
-        step Subprocess(Client::Connect), id: :connect
+        step Subprocess(Client::Connect), id: :connect,
+          Output(:failure) => End(:failure)
         step :retrieve_document
+        fail :error_for_retrieve
         step :store_document
 
         def retrieve_document(ctx, session:, diagram_slug:, **)
@@ -25,6 +27,10 @@ def retrieve_document(ctx, session:, diagram_slug:, **)
         def store_document(ctx, pro_json_document:, target_filename:, **)
           File.write(target_filename, pro_json_document) > 0
         end
+
+        def error_for_retrieve(ctx, response:, diagram_slug:, **)
+          ctx[:error_message] = %(Diagram #{diagram_slug.inspect} couldn't be retrieved. HTTP status: #{response.status})
+        end
       end
 
     end # Editor

test/api_test.rb

@@ -39,11 +39,22 @@ class ApiTest < Minitest::Spec
 
     # TODO: use endpoint to run, and 404, 401 paths
     assert_equal signal.inspect, %(#<Trailblazer::Activity::End semantic=:failure>)
+    assert_equal ctx[:error_message], %(Diagram "xxxfff" couldn't be retrieved. HTTP status: 401)
 
     assert_equal File.exist?("test/imported_json/xxxfff.json"), false
   end
 
   it "401 unauthorized because wrong token" do
+    Trailblazer::Pro.initialize!(api_key: "XXX api_key", trailblazer_pro_host: trailblazer_pro_host)
 
+    signal, (ctx, _) = Trailblazer::Developer.wtf?(Trailblazer::Pro::Editor::Import, [{
+        diagram_slug: "b0f945",
+        target_filename: "test/imported_json/b0f945.json",
+        session: Trailblazer::Pro::Session.session
+      },
+      {}
+    ])
+
+    assert_equal ctx[:error_message], %(Custom token couldn't be retrieved. HTTP status: 401)
   end
 end