Tween: Add null check for target object

Fixes #45399.

(cherry picked from commit 5b2100d85c6b021ffe019552e5664719aed094e9)

scene/animation/tween.cpp

@@ -1342,6 +1342,9 @@ bool Tween::interpolate_property(Object *p_object, NodePath p_property, Variant
 		return true;
 	}
 
+	// Check that the target object is valid
+	ERR_FAIL_COND_V_MSG(p_object == nullptr, false, vformat("The Tween \"%s\"'s target node is `null`. Is the node reference correct?", get_name()));
+
 	// Get the property from the node path
 	p_property = p_property.get_as_property_path();
 
@@ -1365,6 +1368,9 @@ bool Tween::interpolate_method(Object *p_object, StringName p_method, Variant p_
 		return true;
 	}
 
+	// Check that the target object is valid
+	ERR_FAIL_COND_V_MSG(p_object == nullptr, false, vformat("The Tween \"%s\"'s target node is `null`. Is the node reference correct?", get_name()));
+
 	// Convert any integers into REALs as they are better for interpolation
 	if (p_initial_val.get_type() == Variant::INT) p_initial_val = p_initial_val.operator real_t();
 	if (p_final_val.get_type() == Variant::INT) p_final_val = p_final_val.operator real_t();