Does this issue occur when all extensions are disabled?: Yes/No

• VS Code Version: 1.101.0
• OS Version: Win 11

The handling of the result of an ${input} variable type command in a tasks.json file has changed.

  "inputs": [
    {
      "id": "pickOption",
      "type": "command",
      "command": "myextension.pickOption",
      "args": {
        "description": "Pick an option"
      }
    }
  ]

It is no longer possible to abandon the task by returning undefined from the command.
If I use an ${input} variable type pickString in a tasks.json and I press Esc the task is abandoned.

  "inputs": [
    {
      "id": "pickOptionNative",
      "type": "pickString",
      "description": "Pick an option (Native)",
      "options": ["Option A", "Option B", "Option C", "Option D"]
    }
  ]

Looking at the source code: baseConfigurationResolverService.ts

The code for pickString returns undefined if the user abandons the quickPick, (line 322-329)

The code for command always returns: return { value: result, input: info };
This is correct if the return value of the command is a string, but not if it is undefined or null.

In commit 81775e7 (2025-03-11) it was:

						if (typeof result === 'string' || Types.isUndefinedOrNull(result)) {
							return result;
						}

In commit 4c95d54 (2025-03-18) it has changed to:

						if (typeof result === 'string' || Types.isUndefinedOrNull(result)) {
							return { value: result, input: info };
						}

Now an undefined result is treated as a valid result.
Better would this be to change it to:

						if (typeof result === 'string') {
							return { value: result, input: info };
						}
						if (Types.isUndefinedOrNull(result)) {
							return undefined;
						}