Compiler run failed

[porco-rosso-j]

solidity compiler threw the error below when I ran npm run build.

Missing dependencies found. Installing now...

[⠆] Compiling...
[⠢] Compiling 68 files with 0.8.17
[⠆] Solc 0.8.17 finished in 763.48ms
Error: 
Compiler run failed
error[4113]: DeclarationError: The identifier name "_" is reserved.
  --> src/verifier/ECMaths.sol:39:17:
   |
39 |             let _ := call(39240, 0x0000000000000000000000000000000000000005, 0, freemem, 0xC0, freemem, 0x20)
   |  

what's missing here?