Fix if condition if one of the nodes is undefined while the operator is Or and the other node is true

compiler.go

@@ -452,18 +452,26 @@ func (c *compiler) evalInfixExpression(node *ast.InfixExpression) (interface{},
 
 	lres, err := c.evalExpression(node.Left)
 	if err != nil {
-		return nil, err
+		if _, ok := err.(*ErrUnknownIdentifier); ok {
+			lres = false
+		} else {
+			return nil, err
+		}
 	}
 	if node.Operator == "&&" {
 		if !c.isTruthy(lres) {
 			return false, nil
 		}
 	}
+
 	rres, err := c.evalExpression(node.Right)
 	if err != nil {
-		return nil, err
+		if _, ok := err.(*ErrUnknownIdentifier); !ok {
+			return nil, err
+		} else {
+			rres = false
+		}
 	}
-
 	switch node.Operator {
 	case "&&", "||":
 		return c.boolsOperator(lres, rres, node.Operator)

if_test.go

@@ -260,3 +260,57 @@ func Test_Render_If_Variable_Not_Set(t *testing.T) {
 	r.NoError(err)
 	r.Equal("", s)
 }
+
+func Test_Render_If_Variable_Not_Set_But_Or_Condition_Is_True(t *testing.T) {
+	r := require.New(t)
+	ctx := NewContext()
+	ctx.Set("path", "cart")
+	ctx.Set("paths", "cart")
+	input := `<%= if ( paths == "cart" || (page && page.PageTitle != "cafe") || paths == "cart") { %>hi<%} %>`
+
+	s, err := Render(input, ctx)
+	r.NoError(err)
+	r.Equal("hi", s)
+}
+
+func Test_Render_If_Variable_Not_Set_But_Or_Condition_While_Node_Is_True_Includes_Syntax_Error_Last_Node(t *testing.T) {
+	r := require.New(t)
+	ctx := NewContext()
+	ctx.Set("paths", "cart")
+	input := `<%= if ( paths == "cart" ||  pages ^^^ ) { %>hi<%} %>`
+
+	_, err := Render(input, ctx)
+	r.Error(err)
+}
+
+func Test_Render_If_Variable_Not_Set_But_Or_Condition_While_Node_Is_True_Includes_Syntax_Error_First_Node(t *testing.T) {
+	r := require.New(t)
+	ctx := NewContext()
+	ctx.Set("paths", "cart")
+	input := `<%= if ( paths @#@# "cart" ||  pages) { %>hi<%} %>`
+
+	_, err := Render(input, ctx)
+	r.Error(err)
+}
+
+func Test_Render_If_Variable_Not_Set_But_Or_Condition_Left_Node_Is_True(t *testing.T) {
+	r := require.New(t)
+	ctx := NewContext()
+	ctx.Set("paths", "cart")
+	input := `<%= if ( paths == "cart" ||  pages ) { %>hi<%} %>`
+
+	s, err := Render(input, ctx)
+	r.NoError(err)
+	r.Equal("hi", s)
+}
+
+func Test_Render_If_Variable_Not_Set_But_Or_Condition_Right_Node_Is_True(t *testing.T) {
+	r := require.New(t)
+	ctx := NewContext()
+	ctx.Set("pages", "cart")
+	input := `<%= if ( paths == "cart" ||  pages ) { %>hi<%} %>`
+
+	s, err := Render(input, ctx)
+	r.NoError(err)
+	r.Equal("hi", s)
+}