Cleanup errors

Author: bbrks

base83/base83.go

@@ -1,5 +1,7 @@
 package base83
 
+import "fmt"
+
 const chars = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz#$%*+,-.:;=?@[]^_{|}~"
 
 // lookup table for ASCII->base83 mapping
@@ -27,7 +29,7 @@ func Decode(str string) (val int, err error) {
 	for i := 0; i < len(str); i++ {
 		idx := charLookup[str[i]]
 		if idx == -1 {
-			return 0, invalidError(rune(str[i]), i)
+			return 0, fmt.Errorf("%w: invalid character %q at index %d", ErrInvalidInput, rune(str[i]), i)
 		}
 		val = val*83 + idx
 	}

base83/error.go

@@ -1,11 +1,10 @@
 package base83
 
-import "errors"
+import (
+	"errors"
+)
 
-// ErrInvalidInput is returned when the given input to decode is not valid base83.
-var ErrInvalidInput = errors.New("base83: invalid input")
-
-func invalidError(r rune, i int) error {
-	// No stdlib support for wrapped errors, so return as-is pre-1.13
-	return ErrInvalidInput
-}
+var (
+	// ErrInvalidInput is returned when the given input to decode is not valid base83.
+	ErrInvalidInput = errors.New("base83: invalid input")
+)

decode.go

@@ -1,6 +1,7 @@
 package blurhash
 
 import (
+	"fmt"
 	"image"
 	"image/color"
 	"image/draw"
@@ -12,7 +13,7 @@ import (
 // Components returns the X and Y components of a blurhash.
 func Components(hash string) (x, y int, err error) {
 	if len(hash) < 6 {
-		return 0, 0, ErrInvalidHash
+		return 0, 0, fmt.Errorf("%w: hash too short", ErrInvalidHash)
 	}
 
 	sizeFlag, err := base83.Decode(string(hash[0]))
@@ -26,7 +27,7 @@ func Components(hash string) (x, y int, err error) {
 	expectedLength := 4 + 2*x*y
 	actualLength := len(hash)
 	if expectedLength != actualLength {
-		return 0, 0, lengthError(expectedLength, actualLength)
+		return 0, 0, fmt.Errorf("%w: length mismatch: expected %d, got %d", ErrInvalidHash, expectedLength, actualLength)
 	}
 
 	return x, y, nil
@@ -54,7 +55,7 @@ func NewDecoder() *Decoder {
 // Internal buffers are reused across calls when possible.
 func (d *Decoder) Decode(hash string, width, height, punch int) (image.Image, error) {
 	if width <= 0 || height <= 0 {
-		return nil, ErrInvalidDimensions
+		return nil, fmt.Errorf("%w: had width=%d, height=%d", ErrInvalidDimensions, width, height)
 	}
 	newImg := image.NewNRGBA(image.Rect(0, 0, width, height))
 	if err := d.DecodeDraw(newImg, hash, float64(punch)); err != nil {

decode_test.go

@@ -1,6 +1,7 @@
 package blurhash_test
 
 import (
+	"errors"
 	"image"
 	"image/png"
 	"io"
@@ -82,7 +83,7 @@ func TestComponentsInvalidHash(t *testing.T) {
 		shortHashes := []string{"", "A", "ABCDE"}
 		for _, hash := range shortHashes {
 			_, _, err := blurhash.Components(hash)
-			if err != blurhash.ErrInvalidHash {
+			if !errors.Is(err, blurhash.ErrInvalidHash) {
 				t.Errorf("short hash %q should return ErrInvalidHash, got %v", hash, err)
 			}
 		}
@@ -94,7 +95,7 @@ func TestComponentsInvalidHash(t *testing.T) {
 		if err == nil {
 			t.Fatal("invalid character should return error")
 		}
-		if err != base83.ErrInvalidInput {
+		if !errors.Is(err, base83.ErrInvalidInput) {
 			t.Errorf("expected invalid base83 error, got %v", err)
 		}
 	})
@@ -103,13 +104,13 @@ func TestComponentsInvalidHash(t *testing.T) {
 		// '9' encodes 1x2 components (sizeFlag=9), expecting 4+2*1*2=8 chars
 		// but we provide only 6 chars
 		_, _, err := blurhash.Components("900000")
-		if err != blurhash.ErrInvalidHash {
+		if !errors.Is(err, blurhash.ErrInvalidHash) {
 			t.Errorf("wrong length should return ErrInvalidHash, got %v", err)
 		}
 
 		// Valid 1x1 hash is 6 chars, but provide 8
 		_, _, err = blurhash.Components("00000000")
-		if err != blurhash.ErrInvalidHash {
+		if !errors.Is(err, blurhash.ErrInvalidHash) {
 			t.Errorf("wrong length should return ErrInvalidHash, got %v", err)
 		}
 	})
@@ -173,7 +174,7 @@ func TestDecodeInvalidDimensions(t *testing.T) {
 	for _, tt := range tests {
 		t.Run(tt.name, func(t *testing.T) {
 			_, err := blurhash.Decode(testFixtures[0].hash, tt.width, tt.height, 1)
-			if err != blurhash.ErrInvalidDimensions {
+			if !errors.Is(err, blurhash.ErrInvalidDimensions) {
 				t.Errorf("invalid dimensions should return ErrInvalidDimensions, got %v", err)
 			}
 		})

encode.go

@@ -1,6 +1,7 @@
 package blurhash
 
 import (
+	"fmt"
 	"image"
 	"image/draw"
 	"math"
@@ -39,7 +40,7 @@ func NewEncoder() *Encoder {
 func (e *Encoder) Encode(xComponents, yComponents int, img image.Image) (string, error) {
 	if xComponents < minComponents || xComponents > maxComponents ||
 		yComponents < minComponents || yComponents > maxComponents {
-		return "", ErrInvalidComponents
+		return "", fmt.Errorf("%w: had x=%d, y=%d", ErrInvalidComponents, xComponents, yComponents)
 	}
 
 	bounds := img.Bounds()

error.go

@@ -1,17 +1,14 @@
 package blurhash
 
-import "errors"
-
-// ErrInvalidComponents is returned when components passed to Encode are invalid.
-var ErrInvalidComponents = errors.New("blurhash: must have between 1 and 9 components")
-
-// ErrInvalidHash is returned when the library encounters a hash it can't recognise.
-var ErrInvalidHash = errors.New("blurhash: invalid hash")
-
-// ErrInvalidDimensions is returned when width or height is invalid.
-var ErrInvalidDimensions = errors.New("blurhash: width and height must be positive")
-
-func lengthError(expectedLength, actualLength int) error {
-	// No stdlib support for wrapped errors, so return as-is pre-1.13
-	return ErrInvalidHash
-}
+import (
+	"errors"
+)
+
+var (
+	// ErrInvalidComponents is returned when components passed to Encode are invalid.
+	ErrInvalidComponents = errors.New("blurhash: must have between 1 and 9 components")
+	// ErrInvalidHash is returned when the library encounters a hash it can't recognise.
+	ErrInvalidHash = errors.New("blurhash: invalid hash")
+	// ErrInvalidDimensions is returned when width or height is invalid.
+	ErrInvalidDimensions = errors.New("blurhash: width and height must be positive")
+)