Reproduction steps:

1. Add the attached shader "vulkan_struct_array_issue.shader" to a project
2. Select the shader
3. In the shader's Inspector Window select the dropdown next to "Compile and show code" and set "Custom" and "Vulkan"
4. Click the "Compile and show code" button

Expected result:
Shader compiles for Vulkan without errors

Actual result:
The following errors are printed to the Console Window and are added to the Shader Inspector:
"Shader error in 'vulkan_struct_array_issue': glslang: '' : compilation terminated at line 33 (on vulkan)"
"Shader error in 'vulkan_struct_array_issue': glslang: '[' : array index out of range '4' at line 33 (on vulkan)"

Reproducible in: 2021.2.0a7, 2021.1.0b9, 2020.2.6f1, 2020.1.17f1, 2019.4.21f1, 2018.4.32f1