Pinta 1.7 on Ubuntu 18.04:
1. Menu Edit | Palette | Open.
2. Select "All files" at the bottom right.
3. Select PNG file (which is obviously not palette file). Crash appears:
System.Reflection.TargetInvocationException: Exception has been thrown by the target of an invocation. ---> System.NullReferenceException: Object reference not set to an instance of an object
at Pinta.Core.PaletteFormats.GetLoaderByFilename (System.String fileName) [0x00040] in <e7d0dcd7669a474795360fb5061850db>:0
at Pinta.Core.Palette.Load (System.String fileName) [0x0000b] in <e7d0dcd7669a474795360fb5061850db>:0
at Pinta.Core.EditActions.HandlerPintaCoreActionsEditLoadPaletteActivated (System.Object sender, System.EventArgs e) [0x00174] in <e7d0dcd7669a474795360fb5061850db>:0
at (wrapper managed-to-native) System.Reflection.RuntimeMethodInfo.InternalInvoke(System.Reflection.RuntimeMethodInfo,object,object[],System.Exception&)
at System.Reflection.RuntimeMethodInfo.Invoke (System.Object obj, System.Reflection.BindingFlags invokeAttr, System.Reflection.Binder binder, System.Object[] parameters, System.Globalization.CultureInfo culture) [0x0006a] in <a17fa1457c5d44f2885ac746c1764ea5>:0
--- End of inner exception stack trace ---
at System.Reflection.RuntimeMethodInfo.Invoke (System.Object obj, System.Reflection.BindingFlags invokeAttr, System.Reflection.Binder binder, System.Object[] parameters, System.Globalization.CultureInfo culture) [0x00083] in <a17fa1457c5d44f2885ac746c1764ea5>:0
at System.Reflection.MethodBase.Invoke (System.Object obj, System.Object[] parameters) [0x00000] in <a17fa1457c5d44f2885ac746c1764ea5>:0
at System.Delegate.DynamicInvokeImpl (System.Object[] args) [0x000e7] in <a17fa1457c5d44f2885ac746c1764ea5>:0
at System.MulticastDelegate.DynamicInvokeImpl (System.Object[] args) [0x00008] in <a17fa1457c5d44f2885ac746c1764ea5>:0
at System.Delegate.DynamicInvoke (System.Object[] args) [0x00000] in <a17fa1457c5d44f2885ac746c1764ea5>:0
at GLib.Signal.ClosureInvokedCB (System.Object o, GLib.ClosureInvokedArgs args) [0x0007d] in <ed39f21b9e9343dcbd442a17ad356a9f>:0
at GLib.Signal+SignalClosure.Invoke (GLib.ClosureInvokedArgs args) [0x0000c] in <ed39f21b9e9343dcbd442a17ad356a9f>:0
at GLib.Signal+SignalClosure.MarshalCallback (System.IntPtr raw_closure, GLib.Value* return_val, System.UInt32 n_param_vals, GLib.Value* param_values, System.IntPtr invocation_hint, System.IntPtr marshal_data) [0x00050] in <ed39f21b9e9343dcbd442a17ad356a9f>:0
Confirmed, there should be better error handling for this.