Log platform and disambiguate error message if binary not found (#377)

Author: kaibolay

lib/fastlane/plugin/firebase_app_distribution/actions/firebase_app_distribution_action.rb

@@ -34,8 +34,8 @@ def self.run(params)
         timeout = get_upload_timeout(params)
 
         binary_path = get_binary_path(platform, params)
-        UI.user_error!("Couldn't find binary.") if binary_path.nil?
-        UI.user_error!("Couldn't find binary at path #{binary_path}.") unless File.exist?(binary_path)
+        UI.user_error!("Couldn't determine path for #{platform} binary.") if binary_path.nil?
+        UI.user_error!("Couldn't find #{platform} binary at path #{binary_path}.") unless File.exist?(binary_path)
         binary_type = binary_type_from_path(binary_path)
 
         # TODO(lkellogg): This sets the send timeout for all POST requests made by the client, but

spec/firebase_app_distribution_action_spec.rb

@@ -226,16 +226,16 @@
       allow(action).to receive(:get_authorization).and_return(double('authorization', access_token: 'access-token'))
     end
 
-    it 'raises error if it cannot find a valid binary path' do
+    it 'raises error if it cannot determine a valid binary path' do
       expect do
         action.run(params.merge(ipa_path: nil))
-      end.to raise_error("Couldn't find binary.")
+      end.to raise_error("Couldn't determine path for ios binary.")
     end
 
     it 'raises error if binary does not exist' do
       expect do
         action.run(params)
-      end.to raise_error("Couldn't find binary at path debug.ipa.")
+      end.to raise_error("Couldn't find ios binary at path debug.ipa.")
     end
 
     describe 'with android app' do