Don't allow track playing start if it's not current track

partially fixes #1213

changes/changelog.d/1213.bugfix

@@ -0,0 +1 @@
+Partially fixed playing two tracks at same time (#1213)

front/src/components/audio/Player.vue

@@ -384,6 +384,10 @@ export default {
           })
         },
         onplay: function () {
+          if (this != self.currentSound) {
+            this.stop()
+            return
+          }
           self.$store.commit('player/isLoadingAudio', false)
           self.$store.commit('player/resetErrorCount')
           self.$store.commit('player/errored', false)