Crashes when opening with video argument and clicking seek bar before playback begins

[ColetteDiskette]

Overview Description:
I've been organizing my media library and part of it has involved doing quick tests of video files to make sure they play back well. I was experiencing what I thought were random crashes for a while, and then I narrowed down what was happening. If I click a file to open it in Celluloid, then click on the seek bar to go to somewhere in the middle before the file has started playing back, Celluloid crashes. I've been wanting to just quickly check a couple spots in the middle of videos, then close, and I got a little hasty and found this.

Steps to Reproduce:

1. Open Celluloid with a video file as an argument for playback
2. Try to use the seek bar to move to a later part of the video before playback has a chance to start
3. Wait for when playback would start

Actual Results:
Crash

Expected Results:
Playback to start in the clicked location (or perhaps a disabled seek bar while loading a file)

Version:
0.27 (installed via Arch's extra repo)

Additional Information:
Running Arch Linux, AwesomeWM.

[Uhter]

I have crashes in the same way but also if I open the menu too early (to select subtitles for example).

v0.27-1 on Manjaro Linux.