Merge pull request #2336 from xzyfer/additional-hardening

Additional hardening

src/environment.cpp

@@ -128,8 +128,9 @@ namespace Sass {
   template <typename T>
   void Environment<T>::set_lexical(const std::string& key, T val)
   {
-    auto cur = this; bool shadow = false;
-    while (cur->is_lexical() || shadow) {
+    auto cur = this;
+    bool shadow = false;
+    while ((cur && cur->is_lexical()) || shadow) {
       if (cur->has_local(key)) {
         cur->set_local(key, val);
         return;

src/extend.cpp

@@ -2081,7 +2081,7 @@ namespace Sass {
         error("\"" + str_sel + "\" failed to @extend \"" + str_ext + "\".\n"
               "The selector \"" + str_ext + "\" was not found.\n"
               "Use \"@extend " + str_ext + " !optional\" if the"
-                " extend should be able to fail.", ext->pstate());
+              " extend should be able to fail.", (ext ? ext->pstate() : NULL));
       }
     }
 

src/parser.cpp

@@ -1272,7 +1272,6 @@ namespace Sass {
       bool right_ws = peek < css_comments >() != NULL;
       operators.push_back({ op, left_ws, right_ws });
       operands.push_back(parse_expression());
-      left_ws = peek < css_comments >() != NULL;
     }
     // we are called recursively for list, so we first
     // fold inner binary expression which has delayed