Fix 'Open Scripts Externally' crashing studio.

Closes #369.

CHANGELOG.md

@@ -2,9 +2,13 @@
 
 ## Unreleased Changes
 * Added "EXPERIMENTAL!" label to two-way sync toggle in Rojo's Roblox Studio plugin.
+* Fixed "Open Scripts Externally" feature crashing Studio ([#369][issue-369])
+
+[issue-369]: https://github.com/rojo-rbx/rojo/issues/369
 
 ## [6.1.0][6.1.0] (April 12, 2021)
 * Updated dependencies, fixing OptionalCoordinateFrame-related issues.
+
 * Added `--address` flag to `rojo serve` to allow for external connections. ([#403][pr-403])
 
 [pr-403]: https://github.com/rojo-rbx/rojo/pull/403

plugin/src/ServeSession.lua

@@ -1,4 +1,5 @@
 local StudioService = game:GetService("StudioService")
+local RunService = game:GetService("RunService")
 
 local Log = require(script.Parent.Parent.Log)
 local Fmt = require(script.Parent.Parent.Fmt)
@@ -150,10 +151,18 @@ function ServeSession:__onActiveScriptChanged(activeScript)
 
 	Log.debug("Trying to open script {} externally...", activeScript)
 
-	-- Force-close the script inside Studio
-	local existingParent = activeScript.Parent
-	activeScript.Parent = nil
-	activeScript.Parent = existingParent
+	-- Force-close the script inside Studio... with a small delay in the middle
+	-- to prevent Studio from crashing.
+	spawn(function()
+		local existingParent = activeScript.Parent
+		activeScript.Parent = nil
+
+		for i = 1, 3 do
+			RunService.Heartbeat:Wait()
+		end
+
+		activeScript.Parent = existingParent
+	end)
 
 	-- Notify the Rojo server to open this script
 	self.__apiContext:open(scriptId)