Fixes inability to assign script after clearing

core/object/script_language.cpp

@@ -409,7 +409,9 @@ bool PlaceHolderScriptInstance::set(const StringName &p_name, const Variant &p_v
 	if (values.has(p_name)) {
 		Variant defval;
 		if (script->get_property_default_value(p_name, defval)) {
-			if (defval == p_value) {
+			// The evaluate function ensures that a NIL variant is equal to e.g. an empty Resource.
+			// Simply doing defval == p_value does not do this.
+			if (Variant::evaluate(Variant::OP_EQUAL, defval, p_value)) {
 				values.erase(p_name);
 				return true;
 			}
@@ -419,7 +421,7 @@ bool PlaceHolderScriptInstance::set(const StringName &p_name, const Variant &p_v
 	} else {
 		Variant defval;
 		if (script->get_property_default_value(p_name, defval)) {
-			if (defval != p_value) {
+			if (Variant::evaluate(Variant::OP_NOT_EQUAL, defval, p_value)) {
 				values[p_name] = p_value;
 			}
 			return true;

editor/editor_properties.cpp

@@ -31,6 +31,7 @@
 #include "editor_properties.h"
 
 #include "core/config/project_settings.h"
+#include "core/core_string_names.h"
 #include "editor/editor_file_dialog.h"
 #include "editor/editor_node.h"
 #include "editor/editor_properties_array_dict.h"
@@ -3844,8 +3845,11 @@ void EditorPropertyResource::_resource_selected(const Ref<Resource> &p_resource,
 void EditorPropertyResource::_resource_changed(const Ref<Resource> &p_resource) {
 	// Make visual script the correct type.
 	Ref<Script> s = p_resource;
+
+	// The bool is_script applies only to an object's main script.
+	// Changing the value of Script-type exported variables of the main script should not trigger saving/reloading properties.
 	bool is_script = false;
-	if (get_edited_object() && s.is_valid()) {
+	if (get_edited_object() && s.is_valid() && get_edited_property() == CoreStringNames::get_singleton()->_script) {
 		is_script = true;
 		InspectorDock::get_singleton()->store_script_properties(get_edited_object());
 		s->call("set_instance_base_type", get_edited_object()->get_class());