jitsi: Don't fail when the version of Jitsi doesn't support setReceiv…

…erConstraints

Older versions may not have this method. Try to make the change, but
fail cleanly if it can't be set

Fixes #73

scripts/jitsirtc.js

@@ -945,14 +945,18 @@ class JitsiRTCClient extends AVClient {
      * Uses the new format described here:
      * https://github.com/jitsi/jitsi-videobridge/blob/master/doc/allocation.md
     */
-    this._jitsiConference.setReceiverConstraints({
-      lastN: -1,
-      onStageEndpoints: Object.keys(game.webrtc.client._idCache),
-      defaultConstraints: {
-        maxHeight: 240,
-        maxFrameRate: 30,
-      },
-    });
+    try {
+      this._jitsiConference.setReceiverConstraints({
+        lastN: -1,
+        onStageEndpoints: Object.keys(game.webrtc.client._idCache),
+        defaultConstraints: {
+          maxHeight: 240,
+          maxFrameRate: 30,
+        },
+      });
+    } catch (err) {
+      this.debug("setReceiverConstraints not supported by this Jitsi version; skipping");
+    }
 
     this.debug("User joined:", displayName);