Svace static analyzer fix

Author: Artem Seleznev

schema.go

@@ -181,7 +181,7 @@ func (s *SchemaValidator) Validate(data interface{}) *Result {
 
 	// TODO: this part should be handed over to type validator
 	// Handle special case of json.Number data (number marshalled as string)
-	isnumber := s.Schema.Type.Contains(numberType) || s.Schema.Type.Contains(integerType)
+	isnumber := s.Schema != nil && (s.Schema.Type.Contains(numberType) || s.Schema.Type.Contains(integerType))
 	if num, ok := data.(json.Number); ok && isnumber {
 		if s.Schema.Type.Contains(integerType) { // avoid lossy conversion
 			in, erri := num.Int64()