chore: addresses review comments

Author: jwidauer

Diff for: include/json/value.h

@@ -585,20 +585,20 @@ class JSON_API Value {
   iterator begin();
   iterator end();
 
-  /// @brief Returns a reference to the first element in the container.
-  /// Calling front on an empty container is undefined behavior.
-  Value const& front() const;
+  /// \brief Returns a reference to the first element in the `Value`.
+  /// Requires that this value holds an array or json object, with at least one element.
+  const Value& front() const;
 
-  /// @brief Returns a reference to the last element in the container.
-  /// Calling back on an empty container is undefined behavior.
-  Value const& back() const;
-
-  /// @brief Returns a reference to the first element in the container.
-  /// Calling front on an empty container is undefined behavior.
+  /// \brief Returns a reference to the first element in the `Value`.
+  /// Requires that this value holds an array or json object, with at least one element.
   Value& front();
 
-  /// @brief Returns a reference to the last element in the container.
-  /// Calling back on an empty container is undefined behavior.
+  /// \brief Returns a reference to the last element in the `Value`.
+  /// Requires that value holds an array or json object, with at least one element.
+  const Value& back() const;
+
+  /// \brief Returns a reference to the last element in the `Value`.
+  /// Requires that this value holds an array or json object, with at least one element.
   Value& back();
 
   // Accessors for the [start, limit) range of bytes within the JSON text from
@@ -941,6 +941,14 @@ class JSON_API ValueIterator : public ValueIteratorBase {
 
 inline void swap(Value& a, Value& b) { a.swap(b); }
 
+inline const Value& Value::front() const { return *begin(); }
+
+inline Value& Value::front() { return *begin(); }
+
+inline const Value& Value::back() const { return *(--end()); }
+
+inline Value& Value::back() { return *(--end()); }
+
 } // namespace Json
 
 #pragma pack(pop)

Diff for: src/lib_json/json_value.cpp

@@ -1495,14 +1495,6 @@ Value::iterator Value::end() {
   return iterator();
 }
 
-Value const& Value::front() const { return *begin(); }
-
-Value& Value::front() { return *begin(); }
-
-Value const& Value::back() const { return *(--end()); }
-
-Value& Value::back() { return *(--end()); }
-
 // class PathArgument
 // //////////////////////////////////////////////////////////////////