Use async function instead of explicit promises

src/converse-omemo.js

@@ -729,17 +729,17 @@
                         });
                 },
 
-                generateBundle () {
+                async generateBundle () {
                     /* The first thing that needs to happen if a client wants to
                      * start using OMEMO is they need to generate an IdentityKey
                      * and a Device ID. The IdentityKey is a Curve25519 [6]
                      * public/private Key pair. The Device ID is a randomly
                      * generated integer between 1 and 2^31 - 1.
                      */
-                    const bundle = {};
-                    return libsignal.KeyHelper.generateIdentityKeyPair()
-                        .then(identity_keypair => {
-                            const identity_key = u.arrayBufferToBase64(identity_keypair.pubKey),
+                    const identity_keypair = await libsignal.KeyHelper.generateIdentityKeyPair();
+
+                    const bundle = {},
+                          identity_key = u.arrayBufferToBase64(identity_keypair.pubKey),
                           device_id = generateDeviceID();
 
                     bundle['identity_key'] = identity_key;
@@ -752,23 +752,21 @@
                         },
                         'identity_key': identity_key
                     });
-                            return libsignal.KeyHelper.generateSignedPreKey(identity_keypair, 0);
-                        }).then(signed_prekey => {
+                    const signed_prekey = await libsignal.KeyHelper.generateSignedPreKey(identity_keypair, 0);
+
                     _converse.omemo_store.storeSignedPreKey(signed_prekey);
                     bundle['signed_prekey'] = {
                         'id': signed_prekey.keyId,
                         'public_key': u.arrayBufferToBase64(signed_prekey.keyPair.privKey),
                         'signature': u.arrayBufferToBase64(signed_prekey.signature)
                     }
-                            return Promise.all(_.map(_.range(0, _converse.NUM_PREKEYS), id => libsignal.KeyHelper.generatePreKey(id)));
-                        }).then(keys => {
+                    const keys = await Promise.all(_.map(_.range(0, _converse.NUM_PREKEYS), id => libsignal.KeyHelper.generatePreKey(id)));
                     _.forEach(keys, k => _converse.omemo_store.storePreKey(k.keyId, k.keyPair));
                     const devicelist = _converse.devicelists.get(_converse.bare_jid),
                           device = devicelist.devices.create({'id': bundle.device_id, 'jid': _converse.bare_jid}),
                           marshalled_keys = _.map(keys, k => ({'id': k.keyId, 'key': u.arrayBufferToBase64(k.keyPair.pubKey)}));
                     bundle['prekeys'] = marshalled_keys;
                     device.save('bundle', bundle);
-                        });
                 },
 
                 fetchSession () {