TextMeshPro accepts surrogate pair characters (e.g. emojis), however it doesn't properly handle them causing a crash within the IL2CPP marshaller. This impacts Universal Windows Platform apps when using the TouchScreenKeyboard, e.g. on the HoloLens device, but can be reproed on Windows desktop and may occur on other IL2CPP platforms as well.

Steps:

1. Open the attached Unity project
2. Switch to the Universal Windows Platform (UWP/WSA)
3. Build and Run the app
4. Select the TMP InputField in the bottom-right corner of the window
5. Open the Windows On-Screen keyboard (may need to enable it first in Settings)
6. In the On-Screen keyboard, click the "smiling face"; switches to the "emoji" panel
7. Click on an emoji from the keyboard to enter it into the TMP InputField

Expected: Placeholder characters like "boxes" or '?' are displayed in TMP (doesn't support rendering emoji characters)
Actual: The app hard crashes

NOTE: This bug might impact other platforms in addition to UWP, but it requires a combination of TouchScreenKeyboard input, surrogate pair character input, and IL2CPP back-end