[MM-61076] Fix errcheck issues in server/channels/web/saml.go (#30612)

Co-authored-by: Claude <noreply@anthropic.com>

server/channels/web/saml.go

@@ -155,7 +155,9 @@ func completeSaml(c *Context, w http.ResponseWriter, r *http.Request) {
 				c.LogErrorByCode(err)
 				break
 			}
-			c.App.AddDirectChannels(c.AppContext, teamId, user)
+			if err = c.App.AddDirectChannels(c.AppContext, teamId, user); err != nil {
+				c.LogErrorByCode(err)
+			}
 		}
 	case model.OAuthActionEmailToSSO:
 		if err = c.App.RevokeAllSessions(c.AppContext, user.Id); err != nil {