[GH-28396] Fixed errcheck issues in server/channels/api4/ip_filtering.go (#28441)

* Fixed errcheck issues in server/channels/api4/ip_filtering.go

* Added separate go routine to SendIPFiltersChangedEmail and removed redundant return

* Added import for mlog

* Changed from returning error to logging it

---------

Co-authored-by: Ben Schumacher <ben.schumacher@mattermost.com>

server/.golangci.yml

@@ -82,7 +82,6 @@ issues:
         channels/api4/handlers_test.go|\
         channels/api4/import_test.go|\
         channels/api4/integration_action_test.go|\
-        channels/api4/ip_filtering.go|\
         channels/api4/ip_filtering_test.go|\
         channels/api4/job_test.go|\
         channels/api4/license.go|\

server/channels/api4/ip_filtering.go

@@ -8,6 +8,7 @@ import (
 	"net/http"
 
 	"github.com/mattermost/mattermost/server/public/model"
+	"github.com/mattermost/mattermost/server/public/shared/mlog"
 	"github.com/mattermost/mattermost/server/v8/channels/app"
 	"github.com/mattermost/mattermost/server/v8/channels/audit"
 	"github.com/mattermost/mattermost/server/v8/einterfaces"
@@ -81,7 +82,11 @@ func applyIPFilters(c *Context, w http.ResponseWriter, r *http.Request) {
 
 	auditRec.Success()
 
-	go c.App.SendIPFiltersChangedEmail(c.AppContext, c.AppContext.Session().UserId)
+	go func() {
+		if err := c.App.SendIPFiltersChangedEmail(c.AppContext, c.AppContext.Session().UserId); err != nil {
+			c.Logger.Warn("Failed to send IP filters changed email", mlog.Err(err))
+		}
+	}()
 
 	if err := json.NewEncoder(w).Encode(updatedAllowedRanges); err != nil {
 		c.Err = model.NewAppError("getIPFilters", "api.context.ip_filtering.get_ip_filters.app_error", nil, "", http.StatusInternalServerError).Wrap(err)
@@ -106,5 +111,7 @@ func myIP(c *Context, w http.ResponseWriter, r *http.Request) {
 		return
 	}
 
-	w.Write(json)
+	if _, err := w.Write(json); err != nil {
+		c.Logger.Warn("Error while writing response", mlog.Err(err))
+	}
 }