position_array: Check and use character occupation

While it checked whether each positions are occupied by multiple characters,
it was not reflected in the return value.

This commit fixes this simple issue (along with a typo).

Author: a4lg

ffuzzy/src/compare/position_array.rs

@@ -173,18 +173,18 @@ pub trait BlockHashPositionArrayData {
         }
         let expected_total: u64 = u64_lsb_ones(len as u32);
         let mut total: u64 = 0;
-        self.representation().iter().all(
+        let has_no_multi_occupation = self.representation().iter().all(
             #[inline(always)]
             |&pos| {
-                // Invalid if multiple alphabets are occupy the same position.
+                // Invalid if multiple alphabets occupy the same position.
                 let is_valid = (total & pos) == 0;
                 total |= pos;
                 is_valid
             },
         );
         // All characters in the string must be placed in the position array
         // and no characters may be placed outside the string.
-        total == expected_total
+        has_no_multi_occupation && total == expected_total
     }
 
     /// Performs full validity checking and the normalization test