hrp: small improvement in hrp parsing

Author: tcoratger

src/primitives/hrp.rs

@@ -78,15 +78,15 @@ impl Hrp {
     pub fn parse(hrp: &str) -> Result<Self, Error> {
         use Error::*;
 
-        let mut new = Hrp { buf: [0_u8; MAX_HRP_LEN], size: 0 };
-
         if hrp.is_empty() {
             return Err(Empty);
         }
         if hrp.len() > MAX_HRP_LEN {
             return Err(TooLong(hrp.len()));
         }
 
+        let mut new = Hrp { buf: [0_u8; MAX_HRP_LEN], size: 0 };
+
         let mut has_lower: bool = false;
         let mut has_upper: bool = false;
         for (i, c) in hrp.chars().enumerate() {