+= operator does not work with strings but + does

[PairOfRaggedClaws]

The problem

Describe the bug
Using += to add to a string does not work and generates an unclear error message.

To Reproduce
Steps to reproduce the behavior:

1. In a timeline, assign text to a string variable
   set {var.var1} = "Hello"
2. In a second line, add text using +=
   set {var.var1} += ", world."
3. In a third line, add text using + inbetween two strings
   set {var.var1} = {var.var1} + " darkness, my old friend.

Result: {var.var1} == "Hello darkness, my old friend."

Expected behavior
+= and + should both concatenate strings

Screenshots
n/a

System (please complete the following information):

• OS: MacO@
• Godot Version: 4.4.1
• Dialogic Version: 2.0 Alpha 17 WIP

Solutions

Workaround

use the format {var} = {var} + "string"

Possible fixes