Error on map output and interpolation

Fixes #1246

Author: mgreter

eval.cpp

@@ -890,6 +890,11 @@ namespace Sass {
     } else if (dynamic_cast<Unary_Expression*>(s)) {
       Expression* ex = s->perform(this);
       return evacuate_quotes(interpolation(ex));
+    } else if (dynamic_cast<Map*>(s)) {
+      To_String to_string(&ctx);
+      string dbg(s->perform(&to_string));
+      error(dbg + " isn't a valid CSS value.", s->pstate());
+      return dbg;
     } else {
       To_String to_string(&ctx);
       return evacuate_quotes(s->perform(&to_string));

output.cpp

@@ -23,6 +23,13 @@ namespace Sass {
     top_nodes.push_back(imp);
   }
 
+  void Output::operator()(Map* m)
+  {
+    To_String to_string(ctx);
+    string dbg(m->perform(&to_string));
+    error(dbg + " isn't a valid CSS value.", m->pstate());
+  }
+
   OutputBuffer Output::get_buffer(void)
   {
 

output.hpp

@@ -35,6 +35,7 @@ namespace Sass {
   public:
     OutputBuffer get_buffer(void);
 
+    virtual void operator()(Map*);
     virtual void operator()(Ruleset*);
     // virtual void operator()(Propset*);
     virtual void operator()(Supports_Block*);