Remove unused types, and fix doc/code mismatch.

CHANGES.md

@@ -2,6 +2,10 @@
 
 ### ? - ?
 
+##### Breaking Changes :mega:
+
+- Removed unused types `JsonValueMissingKey` and `JsonValueNotRealValue` from `CesiumUtility`.
+
 ##### Additions :tada:
 
 - Added `offset` getter to `AccessorView`.
@@ -1123,4 +1127,4 @@ In addition to the above, this release updates the following third-party librari
 
 ### v0.1.0 - 2021-03-30
 
-- Initial release.
+- Initial release.

CesiumGltf/include/CesiumGltf/AccessorUtility.h

@@ -16,7 +16,7 @@ namespace CesiumGltf {
  */
 struct CountFromAccessor {
   /** @brief Attempts to obtain an element count from an empty accessor variant,
-   * resulting in -1. */
+   * resulting in 0. */
   int64_t operator()(std::monostate) { return 0; }
 
   /** @brief Attempts to obtain an element count from an \ref AccessorView. */

CesiumUtility/include/CesiumUtility/JsonValue.h

@@ -16,25 +16,6 @@
 
 namespace CesiumUtility {
 
-/**
- * @deprecated JSON parsing no longer throws this exception.
- */
-struct JsonValueMissingKey : public std::runtime_error {
-  /**
-   * @brief Creates a new \ref JsonValueMissingKey exception for the given key.
-   */
-  JsonValueMissingKey(const std::string& key)
-      : std::runtime_error(key + " is not present in Object") {}
-};
-
-/**
- * @deprecated JSON parsing no longer throws this exception.
- */
-struct JsonValueNotRealValue : public std::runtime_error {
-  JsonValueNotRealValue()
-      : std::runtime_error("this->value was not double, uint64_t or int64_t") {}
-};
-
 /**
  * @brief Attempts a narrowing conversion of `U` into `T` without losing
  * information. If a lossless conversion can't be performed, `std::nullopt` is