Fix jumpToTime

Fixes #801

src/renderer/controllers/playback-controller.js

@@ -93,6 +93,10 @@ module.exports = class PlaybackController {
 
   // Skip (aka seek) to a specific point, in seconds
   skipTo (time) {
+    if (!Number.isFinite(time)) {
+      console.error('Tried to skip to a non-finite time ' + time)
+      return console.trace()
+    }
     if (isCasting(this.state)) Cast.seek(time)
     else this.state.playing.jumpToTime = time
   }

src/renderer/lib/cast.js

@@ -396,7 +396,9 @@ function stop () {
 
 function stoppedCasting () {
   state.playing.location = 'local'
-  state.playing.jumpToTime = state.playing.currentTime
+  state.playing.jumpToTime = Number.isFinite(state.playing.currentTime)
+    ? state.playing.currentTime
+    : 0
   update()
 }