Return a custom error from BART text2text if sequence is too long

instead of panicking

pkg/tasks/text2text/bart/text2text.go

@@ -135,6 +135,10 @@ func (m *Text2Text) Generate(ctx context.Context, text string, opts *text2text.O
 	if err != nil {
 		return text2text.Response{}, err
 	}
+	if l, max := len(tokenized), m.Model.Bart.Config.MaxLength; l > max {
+		return text2text.Response{}, fmt.Errorf("%w: %d > %d", text2text.ErrInputSequenceTooLong, l, max)
+	}
+
 	sequences, scores := m.process(ctx, tokenized, *opts)
 	result := text2text.Response{
 		Texts:  make([]string, len(sequences)),

pkg/tasks/text2text/text2text.go

@@ -6,6 +6,7 @@ package text2text
 
 import (
 	"context"
+	"errors"
 	"fmt"
 	"strings"
 
@@ -76,6 +77,10 @@ type Response struct {
 	Scores []float64
 }
 
+// ErrInputSequenceTooLong means that pre-processing the input text
+// produced a sequence that exceeds the maximum allowed length.
+var ErrInputSequenceTooLong = errors.New("input sequence too long")
+
 // DefaultOptions returns the default options for generating text.
 func DefaultOptions() *Options {
 	return &Options{