more targeted regex for export matching

Author: ChrLackner

webgpu/link/__init__.py

@@ -1,3 +1,11 @@
+import re
 from pathlib import Path
 
-js_code = (Path(__file__).parent / "link.js").read_text().replace("export ", "")
+_link_js_path = Path(__file__).parent / "link.js"
+if not _link_js_path.exists():
+    raise FileNotFoundError(
+        f"webgpu link.js not found at {_link_js_path}. "
+        "The webgpu package may be installed incorrectly."
+    )
+
+js_code = re.sub(r"^export ", "", _link_js_path.read_text(), flags=re.MULTILINE)