sniff: explicitly declare sniff_error_json type; suppress lint warning

src/cmd/sniff.rs

@@ -496,6 +496,7 @@ async fn get_file_to_sniff(args: &Args, tmpdir: &tempfile::TempDir) -> CliResult
  let wtr_file_path;
  #[allow(unused_mut)]
  let mut csv_candidate = true;
+ #[allow(unused_mut)]
  let mut detected_mime = String::new();
 
  #[cfg(all(target_os = "linux", feature = "magic"))]
@@ -781,6 +782,7 @@ pub async fn run(argv: &[&str]) -> CliResult<()> {
  let sfile_info = block_on(future)?;
  let tempfile_to_delete = sfile_info.file_to_sniff.clone();
  #[allow(unused_assignments)]
+ #[allow(unused_mut)]
  let mut file_type = String::new();
 
  // on linux, check what kind of file we have
@@ -1050,7 +1052,7 @@ pub async fn run(argv: &[&str]) -> CliResult<()> {
  };
  Ok(())
  } else {
- let sniff_error_json;
+ let sniff_error_json: serde_json::Value = Default::default();
  #[cfg(all(target_os = "linux", feature = "magic"))]
  {
  sniff_error_json = json!({