chore: Return error if the regex is invalid

src/lib.rs

@@ -28,7 +28,7 @@ fn find_repos(
     let mut warnings = Vec::new();
 
     let exlusion_regex: regex::Regex = regex::Regex::new(&exclusion_pattern.unwrap_or(r"^$"))
-        .unwrap_or_else(|_| regex::Regex::new(r"^$").unwrap());
+        .map_err(|e| format!("invalid regex: {e}"))?;
     for path in tree::find_repo_paths(root)? {
         if exclusion_pattern.is_some() && exlusion_regex.is_match(&path::path_as_string(&path)) {
             warnings.push(format!("[skipped] {}", &path::path_as_string(&path)));