diff --git a/cmd/tmx2img/main.go b/cmd/tmx2img/main.go
index ae6316b..cb2e840 100644
--- a/cmd/tmx2img/main.go
+++ b/cmd/tmx2img/main.go
@@ -43,5 +43,8 @@ func main() {
 		return
 	}
 	defer w.Close()
-	rend.SaveAsPng(w)
+	if err := rend.SaveAsPng(w); err != nil {
+		fmt.Println(err)
+		return
+	}
 }
diff --git a/go.mod b/go.mod
index a99dbc6..f89d3a9 100644
--- a/go.mod
+++ b/go.mod
@@ -4,5 +4,5 @@ go 1.16
 
 require (
 	github.com/disintegration/imaging v1.6.2
-	github.com/stretchr/testify v1.8.0
+	github.com/stretchr/testify v1.8.1
 )
diff --git a/go.sum b/go.sum
index 47d8531..0e16bdc 100644
--- a/go.sum
+++ b/go.sum
@@ -7,9 +7,11 @@ github.com/pmezard/go-difflib v1.0.0 h1:4DBwDE0NGyQoBHbLQYPwSUPoCMWR5BEzIk/f1lZb
 github.com/pmezard/go-difflib v1.0.0/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4=
 github.com/stretchr/objx v0.1.0/go.mod h1:HFkY916IF+rwdDfMAkV7OtwuqBVzrE8GR6GFx+wExME=
 github.com/stretchr/objx v0.4.0/go.mod h1:YvHI0jy2hoMjB+UWwv71VJQ9isScKT/TqJzVSSt89Yw=
+github.com/stretchr/objx v0.5.0/go.mod h1:Yh+to48EsGEfYuaHDzXPcE3xhTkx73EhmCGUpEOglKo=
 github.com/stretchr/testify v1.7.1/go.mod h1:6Fq8oRcR53rry900zMqJjRRixrwX3KX962/h/Wwjteg=
-github.com/stretchr/testify v1.8.0 h1:pSgiaMZlXftHpm5L7V1+rVB+AZJydKsMxsQBIJw4PKk=
 github.com/stretchr/testify v1.8.0/go.mod h1:yNjHg4UonilssWZ8iaSj1OCr/vHnekPRkoO+kdMU+MU=
+github.com/stretchr/testify v1.8.1 h1:w7B6lhMri9wdJUVmEZPGGhZzrYTPvgJArz7wNPgYKsk=
+github.com/stretchr/testify v1.8.1/go.mod h1:w2LPCIKwWwSfY2zedu0+kehJoqGctiVI29o6fzry7u4=
 golang.org/x/image v0.0.0-20191009234506-e7c1f5e7dbb8 h1:hVwzHzIUGRjiF7EcUjqNxk3NCfkPxbDKRdnNE1Rpg0U=
 golang.org/x/image v0.0.0-20191009234506-e7c1f5e7dbb8/go.mod h1:FeLwcggjj3mMvU+oOTbSwawSJRM1uh48EjtB4UJZlP0=
 golang.org/x/text v0.3.0/go.mod h1:NqM8EUOU14njkJ3fqMW+pc6Ldnwhi/IjpwHt7yyuwOQ=
diff --git a/tiled_test.go b/tiled_test.go
index 6a47421..1a36769 100644
--- a/tiled_test.go
+++ b/tiled_test.go
@@ -377,7 +377,7 @@ func TestParseHexColor(t *testing.T) {
 
 	for _, c := range cases {
 		color := &HexColor{}
-		color.UnmarshalXMLAttr(c.attr)
+		assert.NoError(t, color.UnmarshalXMLAttr(c.attr))
 		assert.Equal(t, c.color, color.c, c.name)
 	}
 }
diff --git a/tmx_data.go b/tmx_data.go
index 0dbb0f6..ed4dbe6 100644
--- a/tmx_data.go
+++ b/tmx_data.go
@@ -29,15 +29,12 @@ import (
 	"encoding/base64"
 	"errors"
 	"io"
-	"io/ioutil"
 	"strconv"
 	"strings"
 )
 
-var (
-	// ErrUnknownCompression error is returned when file contains invalid compression method
-	ErrUnknownCompression = errors.New("tiled: invalid compression method")
-)
+// ErrUnknownCompression error is returned when file contains invalid compression method
+var ErrUnknownCompression = errors.New("tiled: invalid compression method")
 
 // Data is raw data
 type Data struct {
@@ -82,7 +79,7 @@ func (d *Data) decodeBase64() (data []byte, err error) {
 		return
 	}
 
-	return ioutil.ReadAll(comr)
+	return io.ReadAll(comr)
 }
 
 func (d *Data) decodeCSV() ([]uint32, error) {
diff --git a/tmx_map.go b/tmx_map.go
index d3b0f48..e5f68d0 100644
--- a/tmx_map.go
+++ b/tmx_map.go
@@ -203,7 +203,9 @@ func (m *Map) UnmarshalXML(d *xml.Decoder, start xml.StartElement) error {
 
 	// Decode object groups.
 	for _, g := range item.ObjectGroups {
-		g.DecodeObjectGroup((*Map)(&item))
+		if err := g.DecodeObjectGroup((*Map)(&item)); err != nil {
+			return err
+		}
 	}
 
 	*m = (Map)(item)
diff --git a/tmx_object.go b/tmx_object.go
index c054861..22fb9d3 100644
--- a/tmx_object.go
+++ b/tmx_object.go
@@ -30,10 +30,8 @@ import (
 	"strings"
 )
 
-var (
-	// ErrInvalidObjectPoint error is returned if there is error parsing object points
-	ErrInvalidObjectPoint = errors.New("tiled: invalid object point")
-)
+// ErrInvalidObjectPoint error is returned if there is error parsing object points
+var ErrInvalidObjectPoint = errors.New("tiled: invalid object point")
 
 // ObjectGroup is in fact a map layer, and is hence called "object layer" in Tiled Qt
 type ObjectGroup struct {
@@ -64,18 +62,23 @@ type ObjectGroup struct {
 }
 
 // DecodeObjectGroup decodes object group data
-func (g *ObjectGroup) DecodeObjectGroup(m *Map) {
+func (g *ObjectGroup) DecodeObjectGroup(m *Map) error {
 	for _, object := range g.Objects {
 		if object.GID > 0 {
 			// Initialize all tilesets that are referenced by tile objects. Otherwise,
 			// if a tileset is used by an object tile but not used by any layer it
 			// won't be loaded.
-			m.TileGIDToTile(object.GID)
+			if _, err := m.TileGIDToTile(object.GID); err != nil {
+				return err
+			}
 		}
 		if len(object.TemplateSource) > 0 {
-			object.initTemplate(m)
+			if err := object.initTemplate(m); err != nil {
+				return err
+			}
 		}
 	}
+	return nil
 }
 
 // UnmarshalXML decodes a single XML element beginning with the given start element.
@@ -181,8 +184,7 @@ func (o *Object) UnmarshalXML(d *xml.Decoder, start xml.StartElement) error {
 }
 
 // Ellipse is used to mark an object as an ellipse.
-type Ellipse struct {
-}
+type Ellipse struct{}
 
 // Polygon object is made up of a space-delimited list of x,y coordinates. The origin for these coordinates is the location of the parent object.
 // By default, the first point is created as 0,0 denoting that the point will originate exactly where the object is placed.
diff --git a/tmx_tileset.go b/tmx_tileset.go
index 8599d9f..9bb53ed 100644
--- a/tmx_tileset.go
+++ b/tmx_tileset.go
@@ -123,17 +123,12 @@ type AnimationFrame struct {
 
 // GetTileRect returns a rectangle that contains the tile in the tileset.Image
 func (ts *Tileset) GetTileRect(tileID uint32) image.Rectangle {
-	tilesetTileCount := ts.TileCount
 	tilesetColumns := ts.Columns
 
 	if tilesetColumns == 0 {
 		tilesetColumns = ts.Image.Width / (ts.TileWidth + ts.Spacing)
 	}
 
-	if tilesetTileCount == 0 {
-		tilesetTileCount = (ts.Image.Height / (ts.TileHeight + ts.Spacing)) * tilesetColumns
-	}
-
 	x := int(tileID) % tilesetColumns
 	y := int(tileID) / tilesetColumns