Change some errors to be runtime errors

Author: mgreter

src/ast.cpp

@@ -342,15 +342,15 @@ namespace Sass {
   {
     if (Selector_List_Ptr_Const sl = dynamic_cast<Selector_List_Ptr_Const>(this)) return *sl == rhs;
     if (Simple_Selector_Ptr_Const sp = dynamic_cast<Simple_Selector_Ptr_Const>(this)) return *sp == rhs;
-    throw "invalid selector base classes to compare";
+    throw std::runtime_error("invalid selector base classes to compare");
     return false;
   }
 
   bool Selector::operator< (const Selector& rhs) const
   {
     if (Selector_List_Ptr_Const sl = dynamic_cast<Selector_List_Ptr_Const>(this)) return *sl < rhs;
     if (Simple_Selector_Ptr_Const sp = dynamic_cast<Simple_Selector_Ptr_Const>(this)) return *sp < rhs;
-    throw "invalid selector base classes to compare";
+    throw std::runtime_error("invalid selector base classes to compare");
     return false;
   }
 

src/context.cpp

@@ -562,7 +562,7 @@ namespace Sass {
     }
 
     // abort early if no content could be loaded (various reasons)
-    if (!contents) throw "File to read not found or unreadable: " + input_path;
+    if (!contents) throw std::runtime_error("File to read not found or unreadable: " + input_path);
 
     // store entry path
     entry_path = abs_path;

src/extend.cpp

@@ -1627,11 +1627,11 @@ namespace Sass {
       SourcesSet debugSet;
       debugSet = pNewSelector->sources();
       if (debugSet.size() > 0) {
-        throw "The new selector should start with no sources. Something needs to be cloned to fix this.";
+        throw std::runtime_error("The new selector should start with no sources. Something needs to be cloned to fix this.");
       }
       debugSet = pExtComplexSelector->sources();
       if (debugSet.size() > 0) {
-        throw "The extension selector from our subset map should not have sources. These will bleed to the new selector. Something needs to be cloned to fix this.";
+        throw std::runtime_error("The extension selector from our subset map should not have sources. These will bleed to the new selector. Something needs to be cloned to fix this.");
       }
 #endif
 

src/subset_map.cpp

@@ -6,7 +6,7 @@ namespace Sass {
 
   void Subset_Map::put(const Compound_Selector_Obj& sel, const Subset_Map_Val& value)
   {
-    if (sel->empty()) throw "internal error: subset map keys may not be empty";
+    if (sel->empty()) throw std::runtime_error("internal error: subset map keys may not be empty");
     size_t index = values_.size();
     values_.push_back(value);
     for (size_t i = 0, S = sel->length(); i < S; ++i)