ENH: Values can hold empty vector

Summary

Values should be able to hold empty vector. Before this MR, creating a value with an empty vector does not make this a vector.

See #76 (closed).

Focus

Nothing special.

Test Environment

Run the unit test.

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• Reference related issues
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Check List for the Reviewer

• I understand the intent of this MR
• All automated tests pass
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• Appropriate user and developer documentation (or not necessary)
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include/caosdb/value.h

@@ -37,8 +37,8 @@
       this->wrapped->mutable_list_values()->add_values()->SETTER(value);                           \
     }                                                                                              \
     if (values.empty()) {                                                                          \
-      this->wrapped->mutable_list_values()->add_values()->set_special_value                        \
-        (ProtoSpecialValue::SPECIAL_VALUE_UNSPECIFIED);                                            \
+      this->wrapped->mutable_list_values()->add_values()->set_special_value(                       \
+        ProtoSpecialValue::SPECIAL_VALUE_UNSPECIFIED);                                             \
     }                                                                                              \
   }
 
@@ -389,9 +389,9 @@ public:
     return !IsNull() && this->wrapped->value_case() == ValueCase::kListValues;
   }
   [[nodiscard]] inline auto GetAsVector() const noexcept -> const std::vector<ScalarValue> & {
-    if (!IsVector() || (this->wrapped->list_values().values(0).has_special_value()
-                        && this->wrapped->list_values().values(0).special_value()
-                        == ProtoSpecialValue::SPECIAL_VALUE_UNSPECIFIED)) {
+    if (!IsVector() || (this->wrapped->list_values().values(0).has_special_value() &&
+                        this->wrapped->list_values().values(0).special_value() ==
+                          ProtoSpecialValue::SPECIAL_VALUE_UNSPECIFIED)) {
       // create empty list
       static std::vector<ScalarValue> empty_values;
       return empty_values;