Sharing an image back to element while it's still loading will crash element

**Describe the bug**

Trying to share an image from the fullscreen view of the image while it's still loading, to another room, will crash element.

**To Reproduce**
- click on a very large image in your timeline (mine was 12MB with 6000x8000 resolution)
- while the screen is black/the image is still loading, click the share button and try sharing it to element again
- the app will crash

**Expected behavior**
I expect element not to crash when doing this.

**Smartphone (please complete the following information):**
- Device: Moto G4 Plus
- OS: LineageOS

**Additional context**
- From fdroid, element is version 1.0.12
- Homeserver: matrix.org

Maybe disable the share button while the image is loading, if that's the problem?