Move decoder code into new internal package

Author: oschwald

errors.go

@@ -1,46 +1,13 @@
 package maxminddb
 
-import (
-	"fmt"
-	"reflect"
-)
-
-// InvalidDatabaseError is returned when the database contains invalid data
-// and cannot be parsed.
-type InvalidDatabaseError struct {
-	message string
-}
-
-func newOffsetError() InvalidDatabaseError {
-	return InvalidDatabaseError{"unexpected end of database"}
-}
-
-func newInvalidDatabaseError(format string, args ...any) InvalidDatabaseError {
-	return InvalidDatabaseError{fmt.Sprintf(format, args...)}
-}
+import "github.com/oschwald/maxminddb-golang/v2/internal/mmdberrors"
 
-func (e InvalidDatabaseError) Error() string {
-	return e.message
-}
+type (
+	// InvalidDatabaseError is returned when the database contains invalid data
+	// and cannot be parsed.
+	InvalidDatabaseError = mmdberrors.InvalidDatabaseError
 
-// UnmarshalTypeError is returned when the value in the database cannot be
-// assigned to the specified data type.
-type UnmarshalTypeError struct {
-	Type  reflect.Type
-	Value string
-}
-
-func newUnmarshalTypeStrError(value string, rType reflect.Type) UnmarshalTypeError {
-	return UnmarshalTypeError{
-		Type:  rType,
-		Value: value,
-	}
-}
-
-func newUnmarshalTypeError(value any, rType reflect.Type) UnmarshalTypeError {
-	return newUnmarshalTypeStrError(fmt.Sprintf("%v (%T)", value, value), rType)
-}
-
-func (e UnmarshalTypeError) Error() string {
-	return fmt.Sprintf("maxminddb: cannot unmarshal %s into type %s", e.Value, e.Type)
-}
+	// UnmarshalTypeError is returned when the value in the database cannot be
+	// assigned to the specified data type.
+	UnmarshalTypeError = mmdberrors.UnmarshalTypeError
+)