GDScript reload generates error when created dynamically (no backing script)

[bitwes]

Godot version

v4.0.alpha15.official.432b25d36

System information

OSX 10.15.7

Issue description

When you create a GDScript object, set the source, and then call reload it generates the following error:

ERROR: Attempt to open script '' resulted in error 'File not found'.
   at: load_source_code (modules/gdscript/gdscript.cpp:1064)

Steps to reproduce

This script creates a simple GDScript from a string of source code, creates an instance and calls a method on it.

extends SceneTree

func _init():
	var script_source = '' + \
	"func hello_world():\n" + \
	"\tprint('--- hello world ---')"

	print(script_source)

	var DynScript = GDScript.new()
	DynScript.source_code = script_source
	print('pre-reload')
	DynScript.reload()
	print('post-reload')

	var inst = DynScript.new()
	inst.hello_world()

	quit()

The output shows the error occurs on the reload call.

Godot Engine v4.0.alpha15.official.432b25d36 - https://godotengine.org
Vulkan API 1.1.216 - Using Vulkan Device #0: AMD - AMD Radeon Pro 450
 
Registered camera FaceTime HD Camera (Built-in) with id 1 position 0 at index 0
func hello_world():
        print('--- hello world ---')
pre-reload
ERROR: Attempt to open script '' resulted in error 'File not found'.
   at: load_source_code (modules/gdscript/gdscript.cpp:1064)
post-reload
--- hello world ---

Minimal reproduction project

See steps to reproduce

[L4Vo5]

This can be reproduced with just these two lines

var DynScript = GDScript.new()
DynScript.reload()

The error doesn't happen if a non-empty resource path is set, even if the path is completely invalid

var DynScript = GDScript.new()
DynScript.resource_path = "\n :)"
DynScript.reload()

[bitwes]

With the resource_path trick I was able to get rid of all the error messages with this workaround. It's gross, but there's no more red error messages in my output now.

var _created_script_count = 0
func create_script_from_source(source):
	_created_script_count += 1

	var DynamicScript = GDScript.new()
	DynamicScript.source_code = source
	# The resource_path must be unique or Godot thinks it is trying
	# to load something it has already loaded and generates an error like
	# ERROR: Another resource is loaded from path 'workaround for godot issue #65263' (possible cyclic resource inclusion).
	DynamicScript.resource_path = str('workaround for godot issue #65263 (', _created_script_count, ')')
	var result = DynamicScript.reload()

	return DynamicScript

[adamscott]

I added a check in my PR to not (re)load source code if the path is empty. I needed to do this to handle empty paths with my fix for cyclic references purposes, but it should fix your issue as well.