Undefined behavior for get_script_struct_just_created

[x87]

get_script_struct_just_created does not handle a situation when the new script creation failed.

stream_custom_script {scriptFileName} "this_script_does_not_exist.s"
int ptr = get_script_struct_just_created

ptr will point to a random script in the queue, and there is no indication of error

[x87]

I think it should return nullptr and set condition to false.

stream_custom_script {scriptFileName} "this_script_does_not_exist.s"

int ptr
if not ptr = get_script_struct_just_created
then
  trace "Script creation failed"
end

[x87]

alternatively, stream_custom_script can set condition to false, but this is one of the core opcodes, and any change should be extremely cautious.

if stream_custom_script {scriptFileName} "this_script_does_not_exist.s"
then
   int ptr = get_script_struct_just_created
else
  trace "Script creation failed"
end

[x87]

Also, unit tests for get_script_struct_just_created are not very robust.