Reproduction steps:
1. Open a new or an existing project
2. Go to Edit > Project Settings... > Player > Other Settings
3. Uncheck Auto Graphics API for Linux
4. Move Vulkan above OpenGL Core
5. Build and Run the project

Expected result: The Player starts and everything works
Actual result: The Player crashes if Vulkan drivers are not installed on the system

First 5 lines of the stack trace:
#0 0x007faab8ded3c0 in funlockfile
#1 0x007faab4ae3119 in _init
#2 0x007faab4aeb2bd in vkEnumeratePhysicalDevices
#3 0x007faab9a7e11f in vk::Initialize()
#4 0x007faab9a882b9 in CreateVKGfxDevice()

Reproducible with: 2018.4.32f1, 2019.4.21f1, 2020.2.6f1, 2021.1.0b8, 2021.2.0a6

Notes:
- Make sure to not have Vulkan drivers installed on the system (uninstalled with the command `sudo apt-get remove mesa-vulkan-drivers`)
- If `-force-glcore` is set when starting the Player through the command line, it starts properly
- It has been reported that. on Windows. the Player automatically falls back to the existing Graphics API (e.g. DX11)