modify compile_solidity (#49)

* modify compile_yul

* modified format

* deleted unneccesary comments

* fix error

snark-verifier/src/loader/evm/util.rs

@@ -3,7 +3,7 @@ use crate::{
     util::{arithmetic::PrimeField, Itertools},
 };
 use std::{
-    io::Write,
+    io::{self, Write},
     iter,
     process::{Command, Stdio},
 };
@@ -103,13 +103,22 @@ pub fn estimate_gas(cost: Cost) -> usize {
 
 /// Compile given Solidity `code` into deployment bytecode.
 pub fn compile_solidity(code: &str) -> Vec<u8> {
-    let mut cmd = Command::new("solc")
+    let mut cmd = match Command::new("solc")
         .stdin(Stdio::piped())
         .stdout(Stdio::piped())
         .arg("--bin")
         .arg("-")
         .spawn()
-        .unwrap();
+    {
+        Ok(cmd) => cmd,
+        Err(err) if err.kind() == io::ErrorKind::NotFound => {
+            panic!("Command 'solc' not found");
+        }
+        Err(err) => {
+            panic!("Failed to spawn cmd with command 'solc':\n{err}");
+        }
+    };
+
     cmd.stdin
         .take()
         .unwrap()