installer: use $APPNAME in error messages instead of RiseupVPN

the $APPNAME is a template variable and replace by the gen-qt-installer
script at build time, which allows to have the correct name of the app
on the error message during uninstall

branding/templates/qtinstaller/packages/bitmaskvpn/meta/install.js

@@ -103,14 +103,14 @@ Component.prototype.createOperations = function ()
 function preInstallWindows() {
     console.log("Pre-installation for Windows: check for running bitmask");
     component.addOperation(
-        "Execute", "{1}", "powershell", "-NonInteractive", "-NoProfile", "-command", "try {Get-Process $BINNAME} catch { exit 1}",
-        "errormessage=It seems that an old RiseupVPN client is running. Please exit the app and run this installer again.",
+        "Execute", "{1}", "powershell", "-NonInteractive", "-NoProfile", "-command", "try {Get-Process $BINNAME -ErrorAction Stop} catch { exit 1}",
+        "errormessage=It seems that an old $APPNAME client is running. Please exit the app and run this installer again.",
     );
     /* Remove-Service only introduced in PS 6.0 */
     component.addElevatedOperation(
         "Execute", "{0}", "powershell", "-NonInteractive", "-NoProfile", "-command",
         "try {Get-Service bitmask-helper-v2} catch {exit 0}; try {Stop-Service bitmask-helper-v2} catch {}; try {$$srv = Get-Service bitmask-helper-v2; if ($$srv.Status -eq 'Running') {exit 1} else {exit 0};} catch {exit 0}",
-        "errormessage=It seems that bitmask-helper-v2 service is running, and we could not stop it. Please manually uninstall any previous RiseupVPN or CalyxVPN client and run this installer again.",
+        "errormessage=It seems that bitmask-helper-v2 service is running, and we could not stop it. Please manually uninstall any previous $APPNAME client and run this installer again.",
     );
 }