vesktop: fix permission denied electron build (#476347)

pkgs/by-name/ve/vesktop/package.nix

@@ -88,11 +88,16 @@ stdenv.mkDerivation (finalAttrs: {
     export CSC_IDENTITY_AUTO_DISCOVERY=false
   '';
 
-  # electron builds must be writable on darwin
-  preBuild = lib.optionalString stdenv.hostPlatform.isDarwin ''
-    cp -r ${electron.dist}/Electron.app .
-    chmod -R u+w Electron.app
-  '';
+  # electron builds must be writable
+  preBuild =
+    lib.optionalString stdenv.hostPlatform.isDarwin ''
+      cp -r ${electron.dist}/Electron.app .
+      chmod -R u+w Electron.app
+    ''
+    + lib.optionalString stdenv.hostPlatform.isLinux ''
+      cp -r ${electron.dist} electron-dist
+      chmod -R u+w electron-dist
+    '';
 
   buildPhase = ''
     runHook preBuild
@@ -101,7 +106,7 @@ stdenv.mkDerivation (finalAttrs: {
     pnpm exec electron-builder \
       --dir \
       -c.asarUnpack="**/*.node" \
-      -c.electronDist=${if stdenv.hostPlatform.isDarwin then "." else electron.dist} \
+      -c.electronDist=${if stdenv.hostPlatform.isDarwin then "." else "electron-dist"} \
       -c.electronVersion=${electron.version}
 
     runHook postBuild