Fix linting issues and small mistakes

Author: dsonck92

src/error.rs

@@ -65,7 +65,7 @@ impl ErrorCode {
     /// Return the human-readable description for this error.
     pub fn description(&self) -> &'static str {
         match self {
-            ErrorCode::Unknown => "Unkown error.",
+            ErrorCode::Unknown => "Unknown error.",
             _ => unsafe {
                 CStr::from_ptr(src_strerror(*self as i32))
             }.to_str().unwrap()
@@ -169,7 +169,7 @@ mod tests {
         assert_eq!(ErrorCode::SincPrepareDataBadLen.description(), "Internal error : Bad length in prepare_data ().");
         assert_eq!(ErrorCode::BadInternalState.description(), "Error : Someone is trampling on my internal state.");
         assert_eq!(ErrorCode::MaxError.description(), "Placeholder. No error defined for this error number.");
-        assert_eq!(ErrorCode::Unknown.description(), "Unkown error.");
+        assert_eq!(ErrorCode::Unknown.description(), "Unknown error.");
     }
 
     #[test]

src/samplerate.rs

@@ -314,7 +314,7 @@ mod tests {
         }
         // Drain the remaining resample buffer
         loop {
-            let (input_used, output_generated) = converter.process_into_last(&[0.; 0], &mut resampled_buff).unwrap();
+            let (_, output_generated) = converter.process_into_last(&[0.; 0], &mut resampled_buff).unwrap();
             if output_generated == 0 {
                 break;
             }
@@ -341,16 +341,14 @@ mod tests {
         }
         // Drain the remaining resample buffer
         loop {
-            let (input_used, output_generated) = converter.process_into_last(&[0.; 0], &mut resampled_buff).unwrap();
+            let (_, output_generated) = converter.process_into_last(&[0.; 0], &mut resampled_buff).unwrap();
             if output_generated == 0 {
                 break;
             }
             output.extend(&resampled_buff[..output_generated])
         }
         assert_eq!(output.len(), 44100);
 
-        let mut invalid = 0;
-
         // Expect the difference between all input frames and all output frames to be less than
         // an epsilon.
         let error = input.iter().zip(output).fold(0f32, |max, (input, output)| max.max((input - output).abs()));