exif.go: Just return ErrNoExif without panicking

- For well-defined, high-level errors we prefer to not wrap them with
  stacktraces if the stacktraces add little value. It just makes it more
  labor-intensive to handle those errors effectively (especially
  external ones).

exif.go

@@ -79,12 +79,12 @@ func SearchAndExtractExif(data []byte) (rawExif []byte, err error) {
 			foundAt = i
 			break
 		} else if log.Is(err, ErrNoExif) == false {
-			log.Panic(err)
+			return nil, err
 		}
 	}
 
 	if foundAt == -1 {
-		log.Panic(ErrNoExif)
+		return nil, ErrNoExif
 	}
 
 	return data[foundAt:], nil
@@ -144,7 +144,7 @@ func ParseExifHeader(data []byte) (eh ExifHeader, err error) {
 
 	if len(data) < 2 {
 		exifLogger.Warningf(nil, "Not enough data for EXIF header (1): (%d)", len(data))
-		log.Panic(ErrNoExif)
+		return eh, ErrNoExif
 	}
 
 	byteOrderBytes := [2]byte{data[0], data[1]}
@@ -152,24 +152,24 @@ func ParseExifHeader(data []byte) (eh ExifHeader, err error) {
 	byteOrder, found := ByteOrderLookup[byteOrderBytes]
 	if found == false {
 		// exifLogger.Warningf(nil, "EXIF byte-order not recognized: [%v]", byteOrderBytes)
-		log.Panic(ErrNoExif)
+		return eh, ErrNoExif
 	}
 
 	if len(data) < 4 {
 		exifLogger.Warningf(nil, "Not enough data for EXIF header (2): (%d)", len(data))
-		log.Panic(ErrNoExif)
+		return eh, ErrNoExif
 	}
 
 	fixedBytes := [2]byte{data[2], data[3]}
 	expectedFixedBytes := ExifFixedBytesLookup[byteOrder]
 	if fixedBytes != expectedFixedBytes {
 		// exifLogger.Warningf(nil, "EXIF header fixed-bytes should be [%v] but are: [%v]", expectedFixedBytes, fixedBytes)
-		log.Panic(ErrNoExif)
+		return eh, ErrNoExif
 	}
 
 	if len(data) < 2 {
 		exifLogger.Warningf(nil, "Not enough data for EXIF header (3): (%d)", len(data))
-		log.Panic(ErrNoExif)
+		return eh, ErrNoExif
 	}
 
 	firstIfdOffset := byteOrder.Uint32(data[4:8])