Fixed errcheck issues (#28405)

server/.golangci.yml

@@ -83,7 +83,6 @@ issues:
         channels/api4/group_local.go|\
         channels/api4/group_test.go|\
         channels/api4/handlers_test.go|\
-        channels/api4/image_test.go|\
         channels/api4/import_test.go|\
         channels/api4/integration_action.go|\
         channels/api4/integration_action_test.go|\

server/channels/api4/image_test.go

@@ -75,7 +75,8 @@ func TestGetImage(t *testing.T) {
 
 		handler := http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
 			w.Header().Set("Content-Type", "image/png")
-			w.Write([]byte("success"))
+			_, err := w.Write([]byte("success"))
+			require.NoError(t, err)
 		})
 
 		imageServer := httptest.NewServer(handler)