removes offset method from InvalidEncodingERror (#63)

* removes offset method from `InvalidEncodingERror`

src/token.rs

@@ -61,7 +61,7 @@ impl<'a> Token<'a> {
     /// # use jsonptr::Token;
     /// assert_eq!(Token::from_encoded("~1foo~1~0bar").unwrap().decoded(), "/foo/~bar");
     /// let err = Token::from_encoded("foo/oops~bar").unwrap_err();
-    /// assert_eq!(err.offset(), 3);
+    /// assert_eq!(err.offset, 3);
     /// ```
     ///
     /// ## Errors
@@ -340,13 +340,6 @@ pub struct InvalidEncodingError {
     pub offset: usize,
 }
 
-impl InvalidEncodingError {
-    /// The byte offset of the first invalid `~`.
-    pub fn offset(&self) -> usize {
-        self.offset
-    }
-}
-
 impl fmt::Display for InvalidEncodingError {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
         write!(
@@ -462,12 +455,6 @@ mod tests {
         assert!(Token::from_encoded("a~a").is_err());
     }
 
-    #[test]
-    fn invalid_encoding_offset() {
-        let err = InvalidEncodingError { offset: 3 };
-        assert_eq!(err.offset(), 3);
-    }
-
     #[test]
     fn into_owned() {
         let token = Token::from_encoded("foo~0").unwrap().into_owned();