Rename TypeError to ValueError

A TypeError typically refers to the go type of something. This error is
used to indicate that the value cannot be parsed correctly.

errors.go

@@ -5,9 +5,9 @@ import (
 	"reflect"
 )
 
-// TypeError is an error type returned when param has difficulty deserializing a
-// parameter value.
-type TypeError struct {
+// ValueError is an error type returned when param has difficulty deserializing
+// a parameter value.
+type ValueError struct {
 	// The key that was in error.
 	Key string
 	// The type that was expected.
@@ -17,9 +17,9 @@ type TypeError struct {
 	Err error
 }
 
-func (t TypeError) Error() string {
-	return fmt.Sprintf("param: error parsing key %q as %v: %v", t.Key, t.Type,
-		t.Err)
+func (v ValueError) Error() string {
+	return fmt.Sprintf("param: error parsing key %q as %v: %v",
+		v.Key, v.Type, v.Err)
 }
 
 // SingletonError is an error type returned when a parameter is passed multiple

parse.go

@@ -108,7 +108,7 @@ func parseTextUnmarshaler(key, keytail string, values []string, target reflect.V
 	tu := target.Addr().Interface().(encoding.TextUnmarshaler)
 	err = tu.UnmarshalText([]byte(values[0]))
 	if err != nil {
-		return TypeError{
+		return ValueError{
 			Key:  kpath(key, keytail),
 			Type: target.Type(),
 			Err:  err,
@@ -132,7 +132,7 @@ func parseBool(key, keytail string, values []string, target reflect.Value) error
 		target.SetBool(false)
 		return nil
 	default:
-		return TypeError{
+		return ValueError{
 			Key:  kpath(key, keytail),
 			Type: target.Type(),
 		}
@@ -148,7 +148,7 @@ func parseInt(key, keytail string, values []string, target reflect.Value) error
 
 	i, err := strconv.ParseInt(values[0], 10, t.Bits())
 	if err != nil {
-		return TypeError{
+		return ValueError{
 			Key:  kpath(key, keytail),
 			Type: t,
 			Err:  err.(*strconv.NumError).Err,
@@ -168,7 +168,7 @@ func parseUint(key, keytail string, values []string, target reflect.Value) error
 
 	i, err := strconv.ParseUint(values[0], 10, t.Bits())
 	if err != nil {
-		return TypeError{
+		return ValueError{
 			Key:  kpath(key, keytail),
 			Type: t,
 			Err:  err.(*strconv.NumError).Err,
@@ -188,7 +188,7 @@ func parseFloat(key, keytail string, values []string, target reflect.Value) erro
 
 	f, err := strconv.ParseFloat(values[0], t.Bits())
 	if err != nil {
-		return TypeError{
+		return ValueError{
 			Key:  kpath(key, keytail),
 			Type: t,
 			Err:  err.(*strconv.NumError).Err,