Add ExecuteSafe for avoiding partial output if an error occurs

example_test.go

@@ -1,14 +1,12 @@
 package stick_test
 
 import (
-	"fmt"
-	"os"
-
-	"strconv"
-
 	"bytes"
-
+	"errors"
+	"fmt"
 	"io/ioutil"
+	"os"
+	"strconv"
 
 	"github.com/tyler-sommer/stick"
 )
@@ -25,6 +23,18 @@ func ExampleEnv_Execute() {
 	// Output: Hello, World!
 }
 
+// An example of executing a template that avoids writing any output if an error occurs.
+func ExampleEnv_ExecuteSafe() {
+	env := stick.New(nil)
+
+	params := map[string]stick.Value{"name": "World"}
+	err := env.ExecuteSafe(`Hello, {{ 'world' | fakefilter }}!`, os.Stdout, params)
+	if err != nil {
+		fmt.Println(err)
+	}
+	// Output: Undeclared filter "fakefilter"
+}
+
 type exampleType struct{}
 
 func (e exampleType) Boolean() bool {

stick.go

@@ -1,6 +1,7 @@
 package stick // import "github.com/tyler-sommer/stick"
 
 import (
+	"bytes"
 	"io"
 
 	"github.com/tyler-sommer/stick/parse"
@@ -104,6 +105,16 @@ func (env *Env) Execute(tpl string, out io.Writer, ctx map[string]Value) error {
 	return execute(tpl, out, ctx, env)
 }
 
+// ExecuteSafe executes the template but does not output anything if an error occurs.
+func (env *Env) ExecuteSafe(tpl string, out io.Writer, ctx map[string]Value) error {
+	buf := &bytes.Buffer{}
+	if err := env.Execute(tpl, buf, ctx); err != nil {
+		return err
+	}
+	_, err := io.Copy(out, buf)
+	return err
+}
+
 // Parse loads and parses the given template.
 func (env *Env) Parse(name string) (*parse.Tree, error) {
 	return env.load(name)