fix(ios): dispatch thermal EventChannel callbacks on main queue

[ThadOnTheCouch]

Summary

ProcessInfo.thermalStateDidChangeNotification can be delivered on a background dispatch queue. The current implementation invokes FlutterEventSink directly from onThermalStateChanged, which must run on the main thread. This causes NSInternalInconsistencyException in the Flutter engine when the device thermal state changes (e.g. under memory pressure while backgrounding).

This change:

• Dispatches EventChannel callbacks with DispatchQueue.main.async
• Guards against a nil sink after async hop with [weak self]
• Removes the NotificationCenter observer in onCancel when the stream is cancelled

Reproduction

Observed in production application on Model: iPhone 13 Mini iOS Version:26.5.0 using thermal 1.2.1 when memory pressure + app background coincided with a thermal state notification.

Stack (abbreviated):

Fatal Exception: NSInternalInconsistencyException
SwiftThermalPlugin.onThermalStateChanged
NSProcessInfoNotifyThermalState

Test plan

• Subscribe to onThermalStatusChanged on a physical iOS device
• Trigger thermal/memory pressure (or wait for natural OS notification)
• Confirm app does not crash and stream still receives updates
• Cancel stream subscription and confirm no further observer callbacks

[kevmo314]

Thanks!

[mrgnhnt96]

Hey @kevmo314! 👋

When will this change be available on pub.dev?