Get rid of a couple warning messages.

src/Autocompletion.vala

@@ -45,7 +45,7 @@ public class Autocompletion : Object {
 
 		scrollable_list_view = new ScrollableListView<AutocompletionEntry, AutocompletionEntryView>(
 				entries, typeof(AutocompletionEntry), typeof(AutocompletionEntryView), "entry");
-		stage.add(scrollable_list_view);
+		stage.add_child(scrollable_list_view);
 
 		scrollable_list_view.set_filter_function(filter_function);
 		scrollable_list_view.set_sort_function(sort_function);

src/Command.vala

@@ -105,7 +105,12 @@ public class Command : Object {
 				}
 
 				// Remove remaining placeholders
-				substitute_parameter = placeholder_pattern.replace(substitute_parameter, -1, 0, "");
+				// TODO: handle error properly
+				try {
+					substitute_parameter = placeholder_pattern.replace(substitute_parameter, -1, 0, "");
+				} catch (RegexError e) {
+					stderr.printf("Error in removing remaining placeholders");
+				}
 
 				substitute_command.parameters.add(substitute_parameter);
 			}

src/NestingContainer.vala

@@ -387,6 +387,8 @@ public class NestingContainer : Gtk.Box, NestingContainerChild {
 						Gtk.IconSize.MENU));
 
 			var css_provider = new Gtk.CssProvider();
+			// TODO: handle error properly
+			try {
 			css_provider.load_from_data(
 					".button {\n" +
 					"-GtkButton-default-border: 0px;\n" +
@@ -396,6 +398,9 @@ public class NestingContainer : Gtk.Box, NestingContainerChild {
 					"-GtkWidget-focus-padding: 0px;\n" +
 					"padding: 0px;\n" +
 					"}", -1);
+			} catch (Error e) {
+				stderr.printf("Error in css_provider.load_from_data");
+			}
 			close_button.get_style_context().add_provider(css_provider,
 					Gtk.STYLE_PROVIDER_PRIORITY_APPLICATION);
 

src/Terminal.vala

@@ -227,7 +227,12 @@ public class Terminal : Object {
 					var this_terminal = terminals_by_pid.get((int)child_pid);
 					// Close channel to keep pending shell IO from triggering UI updates (and crashes)
 					// after the corresponding TerminalWidget has been removed
-					this_terminal.command_channel.shutdown(false);
+					// TODO: handle error properly
+					try {
+						this_terminal.command_channel.shutdown(false);
+					} catch (IOChannelError e) {
+						stderr.printf("Error in command_channel.shutdown");
+					}
 					this_terminal.shell_terminated();
 					// TODO: If allowed to run, this loop turns into an infinite loop
 					//       when multiple terminals are used. INVESTIGATE FURTHER!