disallow creating an EncodedString with no data

src/core/EncodedString.cc

@@ -19,12 +19,6 @@ EncodedString::iterator & EncodedString::iterator::operator++()
     return *this;
 }
 
-EncodedString::EncodedString(Encoding::Type encoding)
-    : m_encoding(encoding),
-      m_data(nullptr)
-{
-}
-
 EncodedString::EncodedString(const uint8_t * data, size_t size, Encoding::Type encoding)
     : m_encoding(encoding),
       m_size(size)

src/core/EncodedString.h

@@ -39,7 +39,6 @@ public:
         size_t m_offset;
     };
 
-    EncodedString(Encoding::Type encoding = Encoding::UTF_8);
     EncodedString(const uint8_t * data, size_t size, Encoding::Type encoding = Encoding::UTF_8);
 
     iterator begin() const;