big upgrade UwU

sticker_downloader/errors.py

@@ -0,0 +1,31 @@
+"""Exception types used across the package."""
+
+from __future__ import annotations
+
+
+class StickerDownloaderError(Exception):
+    """Base class for every error raised by this package."""
+
+
+class InvalidPackReference(StickerDownloaderError):
+    """Raised when a string cannot be read as a sticker pack reference."""
+
+
+class InvalidFileType(StickerDownloaderError):
+    """Raised when the user asks for a file type we cannot download."""
+
+
+class FetchError(StickerDownloaderError):
+    """Raised when the CDN returns a non-success status for a file."""
+
+    def __init__(self, url: str, status: int, reason: str = "") -> None:
+        detail = f" ({reason})" if reason else ""
+        super().__init__(f"HTTP {status}{detail} for {url}")
+        self.url = url
+        self.status = status
+        self.reason = reason
+
+    @property
+    def retriable(self) -> bool:
+        """Rate limits and server-side faults are worth another attempt."""
+        return self.status == 429 or self.status >= 500