util/Error: new error passing library

Replaces GLib's GError.

src/decoder/WildmidiDecoderPlugin.cxx

@@ -21,6 +21,7 @@
 #include "WildmidiDecoderPlugin.hxx"
 #include "DecoderAPI.hxx"
 #include "TagHandler.hxx"
+#include "util/Error.hxx"
 #include "fs/Path.hxx"
 #include "fs/FileSystem.hxx"
 #include "system/FatalError.hxx"
@@ -39,10 +40,10 @@ static constexpr unsigned WILDMIDI_SAMPLE_RATE = 48000;
 static bool
 wildmidi_init(const config_param &param)
 {
-	GError *error = nullptr;
+	Error error;
 	const Path path = param.GetBlockPath("config_file",
 					     "/etc/timidity/timidity.cfg",
-					     &error);
+					     error);
 	if (path.IsNull())
 		FatalError(error);