Descriptive errors

[MiguelSavignano]

With the invalid operation, missing document key or missing object key the error is the same JSON::PatchError

Example:
Missing document key path

operations = [{"op": "replace", "value": "BAZZ"}]
item = {foo: "bazz"}
JSON::Patch.new(item, operations).call
# => JSON::PatchError

Invalid operation replaces

operations = [{"op": "replaces", path: "/foo", "value": "BAZZ"}]
item = {foo: "bazz"}
JSON::Patch.new(item, operations).call
# => JSON::PatchError