Allow deleting VMs whose folders are already missing

Remove the saved VM entry on Windows and macOS when its folder has already been deleted. Preserve errors for inaccessible storage and other deletion failures.

Verified through the Windows headless API: the previous build fails with 0x80070002; the rebuilt app removes the VM from the list and vms.cfg. macOS code reviewed; not runtime-tested.

Fixes #146.

src/backend_mac/vm_dir.m

@@ -145,7 +145,12 @@
         /* Leave unrelated files in the VM's disk directory. */
         rmdir(diskDir.fileSystemRepresentation);
     }
-    return [[NSFileManager defaultManager] removeItemAtURL:dir error:error];
+    NSError *removeError = nil;
+    if ([[NSFileManager defaultManager] removeItemAtURL:dir error:&removeError]) return YES;
+    if ([removeError.domain isEqualToString:NSCocoaErrorDomain] &&
+        removeError.code == NSFileNoSuchFileError) return YES;
+    if (error) *error = removeError;
+    return NO;
 }
 
 @end

src/backend_win/asb_core.c

@@ -3847,11 +3847,25 @@ ASB_API HRESULT asb_vm_delete(AsbVm vm)
     if (!get_vm_disk_root(inst->vhdx_path, dir)) return E_INVALIDARG;
     attrs = GetFileAttributesW(dir);
     if (attrs == INVALID_FILE_ATTRIBUTES) {
-        hr = HRESULT_FROM_WIN32(GetLastError());
+        DWORD err = GetLastError();
+        if (err == ERROR_FILE_NOT_FOUND || err == ERROR_PATH_NOT_FOUND) {
+            wchar_t parent[MAX_PATH];
+            DWORD parent_attrs;
+            asb_vm_disk_directory(vm, parent, MAX_PATH);
+            parent_attrs = GetFileAttributesW(parent);
+            if (parent_attrs == INVALID_FILE_ATTRIBUTES)
+                err = GetLastError();
+            else if (!(parent_attrs & FILE_ATTRIBUTE_DIRECTORY))
+                err = ERROR_DIRECTORY;
+            else
+                err = ERROR_SUCCESS;
+        }
+        if (err != ERROR_SUCCESS) {
+            hr = HRESULT_FROM_WIN32(err);
             asb_log(L"Error: VM disk folder is unavailable: %s (0x%08X).", dir, hr);
             return hr;
         }
-    if (!(attrs & FILE_ATTRIBUTE_DIRECTORY)) return HRESULT_FROM_WIN32(ERROR_DIRECTORY);
+    } else if (!(attrs & FILE_ATTRIBUTE_DIRECTORY)) return HRESULT_FROM_WIN32(ERROR_DIRECTORY);
 
     hcs_stop_monitor(inst);
     vm_ssh_proxy_stop(inst);
@@ -3869,7 +3883,7 @@ ASB_API HRESULT asb_vm_delete(AsbVm vm)
     /* Recursively remove the whole VM folder, including subdirectories
        (snapshots\ and the build's _vhdx_staging\); a file-only delete would
        leave those and orphan the dir. */
-    if (!remove_dir_recursive(dir)) {
+    if (attrs != INVALID_FILE_ATTRIBUTES && !remove_dir_recursive(dir)) {
         hr = HRESULT_FROM_WIN32(GetLastError());
         asb_log(L"Error: Cannot remove VM disk folder: %s (0x%08X).", dir, hr);
         save_vm_list();