fix(thumbnailer): missing font panic

services/thumbnails/pkg/preprocessor/preprocessor.go

@@ -143,7 +143,11 @@ Scan: // Label for the scanner loop, so we can break it easily
 		textResult.MergeCommon(DefaultMergeMap)
 
 		for _, sRange := range textResult.ScriptRanges {
-			targetFontFace, _ := t.fontLoader.LoadFaceForScript(sRange.TargetScript)
+			targetFontFace, err := t.fontLoader.LoadFaceForScript(sRange.TargetScript)
+			if err != nil {
+				return nil, err
+			}
+
 			// if the target script is "_unknown" it's expected that the loaded face
 			// uses the default font
 			faceHeight := targetFontFace.Face.Metrics().Height

services/thumbnails/pkg/preprocessor/preprocessor_test.go

@@ -149,6 +149,17 @@ var _ = Describe("ImageDecoder", func() {
 			Expect(err).ToNot(HaveOccurred())
 			Expect(img).ToNot(BeNil())
 		})
+
+		It("fails if the font is missing", func() {
+			decoder.fontLoader.fontMapData = &FontMapData{
+				FMap: &FontMap{
+					DefaultFont: "/some/unknown/font.otf",
+				},
+			}
+			img, err := decoder.Convert(bytes.NewReader([]byte("This is a test text")))
+			Expect(err).To(HaveOccurred())
+			Expect(img).To(BeNil())
+		})
 	})
 
 	Describe("test ForType", func() {

services/thumbnails/pkg/service/grpc/v0/service.go

@@ -12,13 +12,14 @@ import (
 	rpc "github.com/cs3org/go-cs3apis/cs3/rpc/v1beta1"
 	provider "github.com/cs3org/go-cs3apis/cs3/storage/provider/v1beta1"
 	"github.com/golang-jwt/jwt/v5"
+	"github.com/pkg/errors"
+	merrors "go-micro.dev/v4/errors"
+	"google.golang.org/grpc/metadata"
+
 	revactx "github.com/opencloud-eu/reva/v2/pkg/ctx"
 	"github.com/opencloud-eu/reva/v2/pkg/rgrpc/todo/pool"
 	"github.com/opencloud-eu/reva/v2/pkg/storagespace"
 	"github.com/opencloud-eu/reva/v2/pkg/utils"
-	"github.com/pkg/errors"
-	merrors "go-micro.dev/v4/errors"
-	"google.golang.org/grpc/metadata"
 
 	"github.com/opencloud-eu/opencloud/pkg/log"
 	thumbnailssvc "github.com/opencloud-eu/opencloud/protogen/gen/opencloud/services/thumbnails/v0"
@@ -169,6 +170,10 @@ func (g Thumbnail) handleCS3Source(ctx context.Context, req *thumbnailssvc.GetTh
 	}
 	pp := preprocessor.ForType(sRes.GetInfo().GetMimeType(), ppOpts)
 	img, err := pp.Convert(r)
+	if err != nil {
+		g.logger.Error().Err(err).Msg("failed to convert image")
+	}
+
 	if img == nil || err != nil {
 		return "", merrors.NotFound(g.serviceID, "could not get image")
 	}