Show startup errors in a desktop notification

This should make it much easier to spot what goes wrong if you're new to
yabridge and don't know where to look yet.

CHANGELOG.md

@@ -10,11 +10,11 @@ Versioning](https://semver.org/spec/v2.0.0.html).
 
 ### Added
 
-- When the Wine plugin host process fails to start, yabridge will now show a
-  desktop notification to notify you about this. This lets you diagnose issues
-  faster if you didn't already start your DAW from a terminal. These
-  notifications require `libnotify` and the `notify-send` application to be
-  installed.
+- When a plugin fails to load or when the Wine plugin host process fails to
+  start, yabridge will now show you the error in a desktop notification instead
+  of only printing it to the logger. This makes diagnosing issues much faster if
+  you didn't already start your DAW from a terminal. These notifications require
+  `libnotify` and the `notify-send` application to be installed.
 - Added an environment variable to disable the watchdog timer. This allows the
   Wine process to run under a separate namespace. If you don't know that you
   need this, then you probably don't need this!

src/plugin/vst2-plugin.cpp

@@ -53,6 +53,10 @@ extern "C" VST_EXPORT AEffect* VSTPluginMain(
         logger.log("Error during initialization:");
         logger.log(error.what());
 
+        // Also show a desktop notification most people likely won't see the
+        // above message
+        send_notification("Failed to initialize VST2 plugin", error.what());
+
         return nullptr;
     }
 }

src/plugin/vst3-plugin.cpp

@@ -55,6 +55,10 @@ bool InitModule() {
         logger.log("Error during initialization:");
         logger.log(error.what());
 
+        // Also show a desktop notification most people likely won't see the
+        // above message
+        send_notification("Failed to initialize VST3 plugin", error.what());
+
         return false;
     }
 }