fix: add some index checking and fixed a test that relied on type-checking

Signed-off-by: Jesse Simpson <jesse.simpson36@gmail.com>

pkg/engine/engine.go

@@ -347,6 +347,9 @@ func (t TraceableError) ExtractExecutedFunction() (TraceableError, error) {
 	}
 	byteArrayMsg := []byte(t.message)
 	executionLocations := executionLocationRegex.FindAll(byteArrayMsg, -1)
+	if len(executionLocations) == 0 {
+		return t, nil
+	}
 	t.executedFunction = string(executionLocations[0])
 	t.message = strings.ReplaceAll(t.message, t.executedFunction, "")
 	return t, nil
@@ -422,7 +425,12 @@ func cleanupExecError(filename string, err error) error {
 			break
 		}
 		tokens = strings.SplitN(current.Error(), ": ", 3)
-		location = tokens[1]
+		if len(tokens) == 1 {
+			// For cases where the error message doesn't contain a colon
+			location = tokens[0]
+		} else {
+			location = tokens[1]
+		}
 		traceable := TraceableError{
 			location: location,
 			message:  current.Error(),

pkg/engine/engine_test.go

@@ -22,7 +22,6 @@ import (
 	"strings"
 	"sync"
 	"testing"
-	"text/template"
 
 	"github.com/stretchr/testify/assert"
 
@@ -1291,16 +1290,11 @@ func TestRenderTplMissingKeyString(t *testing.T) {
 		t.Errorf("Expected error, got %v", out)
 		return
 	}
-	switch err.(type) {
-	case (template.ExecError):
-		errTxt := fmt.Sprint(err)
-		if !strings.Contains(errTxt, "noSuchKey") {
-			t.Errorf("Expected error to contain 'noSuchKey', got %s", errTxt)
-		}
-	default:
-		// Some unexpected error.
-		t.Fatal(err)
+	errTxt := fmt.Sprint(err)
+	if !strings.Contains(errTxt, "noSuchKey") {
+		t.Errorf("Expected error to contain 'noSuchKey', got %s", errTxt)
 	}
+
 }
 
 func TestNestedHelpersProducesMultilineStacktrace(t *testing.T) {