fix: prevent panic when parsing a URL with no path

Prior to this change `parse` would panic at `src/lib.rs:203:29` with
`index out of bounds: the len is 0 but the index is 0` if given an input
like "git:".

Author: CardboardTurkey

src/lib.rs

@@ -170,6 +170,9 @@ impl GitUrl {
                 normalized.scheme().to_string(),
             ));
         };
+        if normalized.path().is_empty() {
+            return Err(GitUrlParseError::EmptyPath);
+        }
 
         // Normalized ssh urls can always have their first '/' removed
         let urlpath = match &scheme {
@@ -518,6 +521,8 @@ pub enum GitUrlParseError {
     UnsupportedUrlHostFormat,
     #[error("Git Url not in expected format for SSH")]
     UnsupportedSshUrlFormat,
+    #[error("Normalized URL has no path")]
+    EmptyPath,
 
     #[error("Found null bytes within input url before parsing")]
     FoundNullBytes,

tests/parse.rs

@@ -367,6 +367,14 @@ fn ssh_without_organization() {
     assert_eq!(parsed, expected);
 }
 
+#[test]
+fn empty_path() {
+    assert_eq!(
+        GitUrlParseError::EmptyPath,
+        GitUrl::parse("git:").unwrap_err()
+    )
+}
+
 #[test]
 fn bad_port_number() {
     let test_url = "https://github.com:crypto-browserify/browserify-rsa.git";