Refactor AppImage update script execution to improve environment variable handling and error messaging

Author: NeuralFault

StabilityMatrix.Avalonia/ViewModels/Dialogs/UpdateViewModel.cs

@@ -170,11 +170,9 @@ await updateHelper.DownloadUpdate(
                 var updateScriptPath = UpdateHelper.UpdateFolder.JoinFile("update_script.sh").FullPath;
                 var newAppImage = UpdateHelper.ExecutablePath.FullPath;
 
-                var scriptContent = $"""
+                var scriptContent = """
 #!/bin/bash
-PID={Environment.ProcessId}
-NEW_APPIMAGE="{newAppImage.Replace("\"", "\\\"")}"
-OLD_APPIMAGE="{appImage.Replace("\"", "\\\"")}"
+set -e
 
 # Wait for the process to exit
 while kill -0 "$PID" 2>/dev/null; do
@@ -196,15 +194,19 @@ sleep 0.5
                     UnixFileMode.UserRead | UnixFileMode.UserWrite | UnixFileMode.UserExecute
                 );
 
-                System.Diagnostics.Process.Start(
-                    new System.Diagnostics.ProcessStartInfo
-                    {
-                        FileName = "/usr/bin/env",
-                        Arguments = $"bash \"{updateScriptPath}\"",
-                        UseShellExecute = false,
-                        CreateNoWindow = true,
-                    }
-                );
+                var startInfo = new System.Diagnostics.ProcessStartInfo
+                {
+                    FileName = "/usr/bin/env",
+                    Arguments = $"bash \"{updateScriptPath}\"",
+                    UseShellExecute = false,
+                    CreateNoWindow = true,
+                };
+
+                startInfo.EnvironmentVariables["PID"] = Environment.ProcessId.ToString();
+                startInfo.EnvironmentVariables["NEW_APPIMAGE"] = newAppImage;
+                startInfo.EnvironmentVariables["OLD_APPIMAGE"] = appImage;
+
+                System.Diagnostics.Process.Start(startInfo);
 
                 App.Shutdown();
                 return;
@@ -214,7 +216,7 @@ sleep 0.5
                 logger.LogError(ex, "Failed to execute AppImage update script");
 
                 var dialog = DialogHelper.CreateMarkdownDialog(
-                    "AppImage update script failed. \nCould not replace old AppImage with new version. Please check directory permissions. \nFalling back to standard update process. User intervention required: After program closes, \nplease move the new AppImage extracted in the '.StabilityMatrixUpdate' hidden directory to the old AppImage overwriting it. \n\nClose this dialog to continue with standard update process.",
+                    "AppImage update script failed. \nCould not replace old AppImage with new version. Please check directory permissions. \nFalling back to standard update process. User intervention required: \nAfter program closes, \nplease move the new AppImage extracted in the '.StabilityMatrixUpdate' hidden directory to the old AppImage overwriting it. \n\nClose this dialog to continue with standard update process.",
                     Resources.Label_UnexpectedErrorOccurred
                 );