Don't pass null / undefined as attribute value

config/otel_dev/collector-gateway.yaml

@@ -8,7 +8,7 @@ receivers:
             # This can't be '*' because opentelemetry-js uses sendBeacon which always operates
             # in 'withCredentials' mode, which browsers don't allow with an allow-origin of '*'
             #- "https://pr976--element-call.netlify.app"
-            - "https://*"
+            - "http://*"
           allowed_headers:
             - "*"
 processors:

src/otel/OTelGroupCallMembership.ts

@@ -171,7 +171,8 @@ export class OTelGroupCallMembership {
           span.setAttribute("matrix.call.target.userId", userId);
           span.setAttribute("matrix.call.target.deviceId", deviceId);
 
-          const displayName = this.groupCall.room.getMember(userId)?.name;
+          const displayName =
+            this.groupCall.room.getMember(userId)?.name ?? "unknown";
           span.setAttribute("matrix.call.target.displayName", displayName);
           this.callsByCallId.set(call.callId, {
             userId,