Fix crash by freed object assign to typed variable

modules/gdscript/tests/scripts/analyzer/errors/native_freed_instance.gd

@@ -0,0 +1,7 @@
+func test():
+	var x = Node.new()
+
+	x.free()
+
+	var ok = x
+	var bad : Node = x

modules/gdscript/tests/scripts/analyzer/errors/native_freed_instance.out

@@ -0,0 +1,6 @@
+GDTEST_RUNTIME_ERROR
+>> SCRIPT ERROR
+>> on function: test()
+>> analyzer/errors/native_freed_instance.gd
+>> 7
+>> Trying to assign invalid previously freed instance.

modules/gdscript/tests/scripts/analyzer/errors/script_freed_instance.gd

@@ -0,0 +1,10 @@
+class A extends Node:
+	pass
+
+func test():
+	var x = A.new()
+
+	x.free()
+
+	var ok = x
+	var bad : A = x

modules/gdscript/tests/scripts/analyzer/errors/script_freed_instance.out

@@ -0,0 +1,6 @@
+GDTEST_RUNTIME_ERROR
+>> SCRIPT ERROR
+>> on function: test()
+>> analyzer/errors/script_freed_instance.gd
+>> 10
+>> Trying to assign invalid previously freed instance.