MM-25118: fix teamImport panic and return better error (#14797)

Co-authored-by: Mattermod <mattermod@users.noreply.github.com>

api4/team.go

@@ -1138,6 +1138,7 @@ func importTeam(c *Context, w http.ResponseWriter, r *http.Request) {
 	auditRec.AddMeta("from", importFrom)
 
 	var log *bytes.Buffer
+	data := map[string]string{}
 	switch importFrom {
 	case "slack":
 		var err *model.AppError
@@ -1145,12 +1146,14 @@ func importTeam(c *Context, w http.ResponseWriter, r *http.Request) {
 			c.Err = err
 			c.Err.StatusCode = http.StatusBadRequest
 		}
+		data["results"] = base64.StdEncoding.EncodeToString(log.Bytes())
+	default:
+		c.Err = model.NewAppError("importTeam", "api.team.import_team.unknown_import_from.app_error", nil, "", http.StatusBadRequest)
 	}
 
-	data := map[string]string{}
-	data["results"] = base64.StdEncoding.EncodeToString(log.Bytes())
 	if c.Err != nil {
 		w.WriteHeader(c.Err.StatusCode)
+		return
 	}
 	auditRec.Success()
 	w.Write([]byte(model.MapToJson(data)))

api4/team_test.go

@@ -2614,6 +2614,17 @@ func TestImportTeam(t *testing.T) {
 	th := Setup(t).InitBasic()
 	defer th.TearDown()
 
+	th.TestForAllClients(t, func(T *testing.T, c *model.Client4) {
+		data, err := testutils.ReadTestFile("Fake_Team_Import.zip")
+
+		require.False(t, err != nil && len(data) == 0, "Error while reading the test file.")
+		_, resp := th.SystemAdminClient.ImportTeam(data, binary.Size(data), "XYZ", "Fake_Team_Import.zip", th.BasicTeam.Id)
+		CheckBadRequestStatus(t, resp)
+
+		_, resp = th.SystemAdminClient.ImportTeam(data, binary.Size(data), "", "Fake_Team_Import.zip", th.BasicTeam.Id)
+		CheckBadRequestStatus(t, resp)
+	}, "Import from unknown and source")
+
 	t.Run("ImportTeam", func(t *testing.T) {
 		var data []byte
 		var err error

i18n/en.json

@@ -2066,6 +2066,10 @@
     "id": "api.team.import_team.unavailable.app_error",
     "translation": "Malformed request: filesize field is not present."
   },
+  {
+    "id": "api.team.import_team.unknown_import_from.app_error",
+    "translation": "Unknown import source."
+  },
   {
     "id": "api.team.invalidate_all_email_invites.app_error",
     "translation": "Error invalidating email invites."