From d70ea4b82b50545509cfcabb93a9bc85880f661d Mon Sep 17 00:00:00 2001
From: Matthias Friedrich <matt@mafr.de>
Date: Tue, 16 Dec 2025 20:14:59 +0100
Subject: [PATCH 1/2] Add error handling to bundle_css.

---
 src/lib.rs | 24 ++++++++++++++++++++----
 1 file changed, 20 insertions(+), 4 deletions(-)

diff --git a/src/lib.rs b/src/lib.rs
index 6d6421a..3b099f7 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -1,11 +1,11 @@
 use std::collections::HashSet;
 use std::path::Path;
 
-use pyo3::exceptions::PyValueError;
+use pyo3::exceptions::{PyValueError, PyIOError};
 use pyo3::prelude::*;
 
 use browserslist::Error as BrowserslistError;
-use lightningcss::bundler::{Bundler, FileProvider};
+use lightningcss::bundler::{Bundler, FileProvider, BundleErrorKind};
 use lightningcss::stylesheet::{
     MinifyOptions, ParserFlags, ParserOptions, PrinterOptions, StyleSheet,
 };
@@ -49,7 +49,7 @@ fn process_stylesheet(code: &str,
 
     let targets = match mk_targets(browsers_list) {
         Ok(val) => val,
-        Err(e) => {return Err(PyValueError::new_err(format!("browsers_list failed validation: {}", e.to_string())))}
+        Err(e) => {return Err(PyValueError::new_err(format!("Browsers_list failed validation: {}", e.to_string())))}
     };
     let mut stylesheet = match StyleSheet::parse(code, mk_parser_options(filename, error_recovery, parser_flags)) {
         Ok(val) => val,
@@ -142,7 +142,23 @@ fn bundle_css(
             ..Default::default()
         },
     );
-    let mut stylesheet = bundler.bundle(Path::new(path)).unwrap();
+
+    let mut stylesheet = match bundler.bundle(Path::new(path)) {
+        Ok(s) => s,
+        Err(e) => {
+            let message = e.to_string();
+            match e.kind {
+                // Resolver errors, probably related to file I/O
+                BundleErrorKind::ResolverError(_) => {
+                    return Err(PyIOError::new_err(format!("Bundling failed: {}", message)));
+                }
+                // Parser and logical errors
+                _ => {
+                    return Err(PyValueError::new_err(format!("Bundling failed: {}", message)));
+                }
+            }
+        }
+    };
 
     let targets = match mk_targets(browsers_list) {
         Ok(val) => val,

From 38453afe0b7b42eebd1491ee92382b3fe14b1040 Mon Sep 17 00:00:00 2001
From: Matthias Friedrich <matt@mafr.de>
Date: Tue, 16 Dec 2025 22:05:48 +0100
Subject: [PATCH 2/2] Rephrase error message for consistency

---
 src/lib.rs | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/lib.rs b/src/lib.rs
index 3b099f7..43f208d 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -49,7 +49,7 @@ fn process_stylesheet(code: &str,
 
     let targets = match mk_targets(browsers_list) {
         Ok(val) => val,
-        Err(e) => {return Err(PyValueError::new_err(format!("Browsers_list failed validation: {}", e.to_string())))}
+        Err(e) => {return Err(PyValueError::new_err(format!("Validation of browsers_list failed: {}", e.to_string())))}
     };
     let mut stylesheet = match StyleSheet::parse(code, mk_parser_options(filename, error_recovery, parser_flags)) {
         Ok(val) => val,