media: never project zero image/video dimensions (crashes Telegram Desktop on reactions)

internal/app/files/sticker_creator.go

@@ -304,6 +304,10 @@ func (s *Service) prepareStickerSetDocument(ctx context.Context, doc domain.Docu
 
 func (s *Service) ensureStickerMaterialShape(ctx context.Context, doc domain.Document) (domain.Document, error) {
 	mimeType := canonicalStickerMaterialMime(doc.StickerSetMaterialMime())
+	// A stored documentAttributeImageSize with a zero dimension is worse than a
+	// missing one: clients divide by it and crash. Strip any such attribute here
+	// so the branches below re-derive a real 512x512 (or decoded) size.
+	doc.Attributes = dropZeroImageSizeAttributes(doc.Attributes)
 	hasImageSize := false
 	hasVideo := false
 	for _, attr := range doc.Attributes {
@@ -311,7 +315,9 @@ func (s *Service) ensureStickerMaterialShape(ctx context.Context, doc domain.Doc
 		case domain.DocAttrImageSize:
 			hasImageSize = true
 		case domain.DocAttrVideo:
-			hasVideo = true
+			if attr.W > 0 && attr.H > 0 {
+				hasVideo = true
+			}
 		}
 	}
 	switch mimeType {
@@ -444,6 +450,20 @@ func (s *Service) rewriteStickerMaterialBlob(ctx context.Context, docID int64, d
 	return nil
 }
 
+// dropZeroImageSizeAttributes removes documentAttributeImageSize entries whose
+// width or height is not positive. Such an attribute reaches clients as
+// documentAttributeImageSize#0 and is divided by while sizing the render.
+func dropZeroImageSizeAttributes(attrs []domain.DocumentAttribute) []domain.DocumentAttribute {
+	out := attrs[:0:0]
+	for _, a := range attrs {
+		if a.Kind == domain.DocAttrImageSize && (a.W <= 0 || a.H <= 0) {
+			continue
+		}
+		out = append(out, a)
+	}
+	return out
+}
+
 func replaceStickerMaterialFilename(attrs []domain.DocumentAttribute, fallback string) []domain.DocumentAttribute {
 	out := append([]domain.DocumentAttribute(nil), attrs...)
 	for i := range out {