message: Remove system specific detail from error message
diff: @@ -351,12 +351,12 @@ fn save_wasm_to_disk(dir: impl Into<PathBuf>, wasm: &[u8]) -> VmResult<Checksum>
  fn load_wasm_from_disk(dir: impl Into<PathBuf>, checksum: &Checksum) -> VmResult<Vec<u8>> {
  // this requires the directory and file to exist
  let path = dir.into().join(checksum.to_hex());
  - let mut file = File::open(path)
  - .map_err(|e| VmError::cache_err(format!("Error opening Wasm file for reading: {}", e)))?;
  + let mut file =
  + File::open(path).map_err(|_e| VmError::cache_err("Error opening Wasm file for reading"))?;
  let mut wasm = Vec::<u8>::new();
  file.read_to_end(&mut wasm)
  - .map_err(|e| VmError::cache_err(format!("Error reading Wasm file: {}", e)))?;
  + .map_err(|_e| VmError::cache_err("Error reading Wasm file"))?;
  Ok(wasm)
  }
  @@ -518,8 +518,7 @@ mod tests {
  match cache.load_wasm(&checksum).unwrap_err() {
  VmError::CacheErr { msg, .. } => {
  - assert!(msg
  - .starts_with("Error opening Wasm file for reading: No such file or directory"))
  + assert_eq!(msg, "Error opening Wasm file for reading")
  }
  e => panic!("Unexpected error: {:?}", e),
  }
  