[Bug] indexing nested value from slice during mutation causes failed to select

[0rphon]

🐛 Bug Report

Code snippet to reproduce

function main () {
    let x = [0u8; (3, 4)];
    x[0..][0] = [1; 4];     // works
    x[0..][0][0] = 2;       // fails
}

Stack trace & error message

D:\Work\leo-playground>D:\Work\leo_repos\leo\target\release\leo clean && D:\Work\leo_repos\leo\target\release\leo run
      Done Finished in 0 milliseconds 

     Build Starting...
     Build Compiling main program... ("D:\\Work\\leo-playground\\src/main.leo")
      Done Finished in 2 milliseconds

Error:     --> D:\Work\leo-playground\src/main.leo:4:5
     |
   4 |     x[0..][0][0] = 2;       // fails
     |     ^^^^^^^^^^^^^^^^
     |
     = Conditional select gadget failed to select between `2` or `[1, 1, 1, 1]`

Your Environment

• leo commit 2e0dab1
• rustc version 1.55.0-nightly
• Windows 10.0.19043 (Windows 10 Pro) [64-bit]