Test failure path in LLM flow

Author: rowanseymour

test/services/llm.go

@@ -2,6 +2,7 @@ package services
 
 import (
 	"context"
+	"errors"
 	"strings"
 
 	"github.com/nyaruka/goflow/flows"
@@ -16,9 +17,11 @@ func NewLLM() *LLMService {
 
 func (s *LLMService) Response(ctx context.Context, instructions, input string, maxTokens int) (*flows.LLMResponse, error) {
 	var output string
-	if strings.HasPrefix(input, "\\return ") { // an input like "\return foo" will return "foo"
+	if strings.HasPrefix(input, "\\error ") { // an input like "\error foo" will return the error "foo"
+		return nil, errors.New(input[7:])
+	} else if strings.HasPrefix(input, "\\return ") { // an input like "\return foo" will return "foo"
 		output = input[8:]
-	} else if strings.HasPrefix(input, "Categorize") { // instructions like "Categorize... Category2, Category3" will return "Category3"
+	} else if strings.HasPrefix(instructions, "Categorize") { // instructions like "Categorize... Category2, Category3" will return "Category3"
 		words := strings.Fields(instructions)
 		output = words[len(words)-1]
 	} else {