Allow -1 characters while reading a file

src/App.cpp

@@ -298,7 +298,8 @@ static std::string read_whole_file(std::ifstream& file)
   while(file.good())
   {
     char ch = file.get();
-    if(ch != -1) result.push_back(ch);
+    if(!file.good()) break;
+    result.push_back(ch);
   }
   return std::move(result);
 }