DE-1328 Fix GetStoredAttachment and add nilaway

.github/workflows/main.yml

@@ -4,40 +4,35 @@ on:
   pull_request:
     branches: [ master, main ]
   push:
-    branches: [master, main ]
+    branches: [ master, main ]
 
 jobs:
   test:
     name: test
     strategy:
       matrix:
         go-version:
-          - 1.18.x
-          - 1.19.x
-          - 1.20.x
+          - 1.22.x
+          - 1.23.x
         os: [ ubuntu-latest ]
     runs-on: ${{ matrix.os }}
     steps:
       - name: Checkout
         uses: actions/checkout@master
 
       - name: Set up Go
-        uses: actions/setup-go@v2
+        uses: actions/setup-go@v3
         with:
           go-version: ${{ matrix.go-version }}
+          cache: true # caching and restoring go modules and build outputs
 
       - run: go env
 
-      - name: Cache deps
-        uses: actions/cache@v2
-        with:
-          path: ~/go/pkg/mod
-          key: ${{ runner.os }}-go-${{ hashFiles('**/go.sum') }}
-          restore-keys: |
-            ${{ runner.os }}-go-
-
       - name: Install deps
         run: go mod download
 
+      - name: nilaway
+        run: make nilaway
+
       - name: Test
         run: go test -v -race -p=1 -count=1

Makefile

@@ -1,15 +1,26 @@
-.PHONY: all
 .DEFAULT_GOAL := all
 
 PACKAGE := github.com/mailgun/mailgun-go
+GOPATH=$(shell go env GOPATH)
+
+NILAWAY = $(GOPATH)/bin/nilaway
+$(NILAWAY):
+	go install go.uber.org/nilaway/cmd/nilaway@latest
 
+.PHONY: all
 all:
 	export GO111MODULE=on; go test . -v
 
+.PHONY: godoc
 godoc:
 	mkdir -p /tmp/tmpgoroot/doc
 	-rm -rf /tmp/tmpgopath/src/${PACKAGE}
 	mkdir -p /tmp/tmpgopath/src/${PACKAGE}
 	tar -c --exclude='.git' --exclude='tmp' . | tar -x -C /tmp/tmpgopath/src/${PACKAGE}
 	echo -e "open http://localhost:6060/pkg/${PACKAGE}\n"
 	GOROOT=/tmp/tmpgoroot/ GOPATH=/tmp/tmpgopath/ godoc -http=localhost:6060
+
+# TODO(vtopc): fix mocks and enable nilaway for them too?
+.PHONY: nilaway
+nilaway: $(NILAWAY)
+	$(NILAWAY) -include-pkgs="$(PACKAGE)" -test=false -exclude-errors-in-files=mock_ ./...

messages.go

@@ -914,6 +914,9 @@ func (mg *MailgunImpl) GetStoredAttachment(ctx context.Context, url string) ([]b
 	r.addHeader("Accept", "message/rfc2822")
 
 	response, err := makeGetRequest(ctx, r)
+	if err != nil {
+		return nil, err
+	}
 
 	return response.Data, err
 }