Bug 1819653

When I run gnome-subtitles on Fedora 32, I get an error:

$ gnome-subtitles 
GLib-GIO | Debug | _g_io_module_get_default: Found default implementation dconf (DConfSettingsBackend) for ‘gsettings-backend’
GLib-GIO | Debug | _g_io_module_get_default: Found default implementation gvfs (GDaemonVfs) for ‘gio-vfs’
GLib | Debug | unsetenv() is not thread-safe and should not be used after threads are created
11:20:31.9 INFO [Spellcheck] Found 24 languages: en_AU,en_BZ,en_CA,en_HK,en_IN,en_IE,en_JM,en_NZ,en_PH,en_SG,en_ZA,en_TT,en_GB,en_US,en_ZW,en_AG,en_BS,en_BW,en_DK,en_GH,en_MW,en_NA,en_NG,en_ZM
Marshaling activate signal
Exception in Gtk# callback delegate
  Note: Applications can use GLib.ExceptionManager.UnhandledException to handle the exception.
System.Reflection.TargetInvocationException: Exception has been thrown by the target of an invocation. ---> GnomeSubtitles.Ui.VideoPreview.Exceptions.PlayerCouldNotInitiateEngineException: Unable to initiate the playbin engine
  at GnomeSubtitles.Ui.VideoPreview.Player.InitializePlaybin () [0x00025] in <f33d384ba6534837888bffb49690ae3f>:0 
  at GnomeSubtitles.Ui.VideoPreview.Player..ctor (Gtk.AspectFrame aspectFrame) [0x00048] in <f33d384ba6534837888bffb49690ae3f>:0 
  at GnomeSubtitles.Ui.VideoPreview.Video.InitializePlayer () [0x00000] in <f33d384ba6534837888bffb49690ae3f>:0 
  at GnomeSubtitles.Ui.VideoPreview.Video..ctor () [0x00059] in <f33d384ba6534837888bffb49690ae3f>:0 
  at GnomeSubtitles.Ui.MainUi..ctor (GnomeSubtitles.Core.EventHandlers handlers) [0x000cc] in <f33d384ba6534837888bffb49690ae3f>:0 
  at GnomeSubtitles.Core.Base.Init () [0x00073] in <f33d384ba6534837888bffb49690ae3f>:0 
  at GnomeSubtitles.Core.Base.<Execute>m__0 () [0x00000] in <f33d384ba6534837888bffb49690ae3f>:0 
  at GnomeSubtitles.Execution.ExecutionContext+<Execute>c__AnonStorey0.<>m__0 (System.Object sender, System.EventArgs e) [0x00000] in <f33d384ba6534837888bffb49690ae3f>: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) [0x0007c] in <51c7842c36134e179a4bb23e01c71109>: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) [0x0009a] in <51c7842c36134e179a4bb23e01c71109>:0 
  at System.Reflection.MethodBase.Invoke (System.Object obj, System.Object[] parameters) [0x00000] in <51c7842c36134e179a4bb23e01c71109>:0 
  at System.Delegate.DynamicInvokeImpl (System.Object[] args) [0x0010d] in <51c7842c36134e179a4bb23e01c71109>:0 
  at System.MulticastDelegate.DynamicInvokeImpl (System.Object[] args) [0x0000b] in <51c7842c36134e179a4bb23e01c71109>:0 
  at System.Delegate.DynamicInvoke (System.Object[] args) [0x00000] in <51c7842c36134e179a4bb23e01c71109>:0 
  at GLib.Signal.ClosureInvokedCB (System.Object o, GLib.ClosureInvokedArgs args) [0x0003d] in <3eb93253711f4c08b41956dc83a81a30>:0 
  at GLib.SignalClosure.Invoke (GLib.ClosureInvokedArgs args) [0x0000c] in <3eb93253711f4c08b41956dc83a81a30>:0 
  at GLib.SignalClosure.MarshalCallback (System.IntPtr raw_closure, System.IntPtr return_val, System.UInt32 n_param_vals, System.IntPtr param_values, System.IntPtr invocation_hint, System.IntPtr marshal_data) [0x00086] in <3eb93253711f4c08b41956dc83a81a30>:0 
  at GLib.ExceptionManager.RaiseUnhandledException (System.Exception e, System.Boolean is_terminal) [0x00000] in <3eb93253711f4c08b41956dc83a81a30>:0 
  at GLib.SignalClosure.MarshalCallback (System.IntPtr raw_closure, System.IntPtr return_val, System.UInt32 n_param_vals, System.IntPtr param_values, System.IntPtr invocation_hint, System.IntPtr marshal_data) [0x00000] in <3eb93253711f4c08b41956dc83a81a30>:0 
  at GLib.Application.g_application_run (System.IntPtr , System.Int32 , System.IntPtr ) [0x00000] in <69f367b3fdca41ca9d926055d3c03a6e>:0 
  at GLib.Application.Run (System.Int32 argc, System.String argv) [0x00000] in <69f367b3fdca41ca9d926055d3c03a6e>:0 
  at GnomeSubtitles.Execution.ExecutionContext.Execute (System.Action methodToExecute) [0x00000] in <f33d384ba6534837888bffb49690ae3f>:0 
  at GnomeSubtitles.Core.Base.Execute (GnomeSubtitles.Execution.ExecutionContext context) [0x00000] in <f33d384ba6534837888bffb49690ae3f>:0 
  at GnomeSubtitles.Execution.Executable.Main (System.String[] args) [0x00000] in <f33d384ba6534837888bffb49690ae3f>:0 




Version-Release number of selected component (if applicable):
gnome-subtitles-1.6-3.fc32.x86_64
gtk-sharp3-2.99.3-29.fc32.x86_64
libgdiplus-6.0.4-2.fc32.x86_64
mono-core-6.6.0-5.fc32.x86_64
mono-data-6.6.0-5.fc32.x86_64
mono-data-sqlite-6.6.0-5.fc32.x86_64
mono-extras-6.6.0-5.fc32.x86_64
mono-locale-extras-6.6.0-5.fc32.x86_64
mono-mvc-6.6.0-5.fc32.x86_64
mono-wcf-6.6.0-5.fc32.x86_64
mono-web-6.6.0-5.fc32.x86_64
mono-winforms-6.6.0-5.fc32.x86_64



Steps to Reproduce:
1. run gnome-subtitles