Coroutines crash on startup.

[piiertho]

Version:
Master branch

OS/device including version:

MacOS Catalina 10.15.3

Issue description:

Coroutines sample crashes on macos when starting, with stacktrace:

Thread 0 Crashed:: Dispatch queue: com.apple.main-thread
0   libsystem_kernel.dylib        	0x00007fff70c3d7fa __pthread_kill + 10
1   libsystem_pthread.dylib       	0x00007fff70cfabc1 pthread_kill + 432
2   libsystem_c.dylib             	0x00007fff70bc4a1c abort + 120
3   libkotlin.dylib               	0x0000000121e46de9 konan::abort() + 9
4   libkotlin.dylib               	0x0000000121e4adae TerminateWithUnhandledException + 14
5   libkotlin.dylib               	0x0000000121e4acf1 KonanTerminateHandler() + 193
6   libc++abi.dylib               	0x00007fff6dc6bdc7 std::__terminate(void (*)()) + 8
7   libc++abi.dylib               	0x00007fff6dc6bb6c __cxxabiv1::failed_throw(__cxxabiv1::__cxa_exception*) + 27
8   libc++abi.dylib               	0x00007fff6dc5d45d __cxa_throw + 113
9   libkotlin.dylib               	0x0000000121e62afc ThrowException + 124
10  libkotlin.dylib               	0x0000000121c70f44 kfun:godot.utils.getMB$godot-library(kotlin.String;kotlin.String)ValueType + 1092 (Utils.kt:15)
11  libkotlin.dylib               	0x0000000121abf94d kfun:godot.Object.$INITIALIZER$lambda-38#internal + 45 (Object.kt:154)
12  libkotlin.dylib               	0x0000000121ac3595 kfun:godot.Object.$$INITIALIZER$lambda-38$FUNCTION_REFERENCE$1438.invoke#internal + 37 (Object.kt:153)
13  libkotlin.dylib               	0x0000000121ac364f kfun:godot.Object.$$INITIALIZER$lambda-38$FUNCTION_REFERENCE$1438.$<bridge-UNN>invoke()ValueType#internal + 143 (Object.kt:153)
14  libkotlin.dylib               	0x000000012186c129 kfun:kotlin.native.concurrent.FreezeAwareLazyImpl.<get-value>()#GENERIC + 2793 (Lazy.kt:52)
15  libkotlin.dylib               	0x0000000121ab958b kfun:godot.Object.<get-toStringMethodBind>#internal + 299 (Object.kt:153)
16  libkotlin.dylib               	0x0000000121abceff kfun:godot.Object.toString()kotlin.String + 143 (Object.kt:357)
17  libkotlin.dylib               	0x0000000121ce39fe kfun:kotlin.godot.entry.udcBridge9$lambda-8#internal + 2030 (Tools.kt:62)
18  libkotlin.dylib               	0x0000000121ce7b1a _knbridge22 + 90 (Entry.kt:109)
19  libkotlin.dylib               	0x0000000121e77b47 ___godot_wrapper_call_and_get + 87
20  org.godotengine.godot         	0x0000000104428ef6 NativeScriptInstance::_ml_call_reversed(NativeScriptDesc*, StringName const&, Variant const**, int) + 182
21  org.godotengine.godot         	0x000000010442aeea NativeScriptInstance::call_multilevel_reversed(StringName const&, Variant const**, int) + 186
22  org.godotengine.godot         	0x00000001059cd836 Navigation2D::_notificationv(int, bool) + 102
23  org.godotengine.godot         	0x0000000106458d83 Object::notification(int, bool) + 19
24  org.godotengine.godot         	0x0000000105549fda Node::_propagate_ready() + 170
25  org.godotengine.godot         	0x0000000105549f69 Node::_propagate_ready() + 57
26  org.godotengine.godot         	0x0000000105549f69 Node::_propagate_ready() + 57
27  org.godotengine.godot         	0x000000010554fa1f Node::_set_tree(SceneTree*) + 95
28  org.godotengine.godot         	0x000000010557e948 SceneTree::init() + 40
29  org.godotengine.godot         	0x0000000104207604 OS_OSX::run() + 52
30  org.godotengine.godot         	0x000000010420a48b main + 811
31  libdyld.dylib                 	0x00007fff70af67fd start + 1

Steps to reproduce:

• Build coroutines sample
• Run it.

Minimal reproduction project:

Coroutines sample project.