custom-functions-metadata - Parenthesized types cause type-mismatch.

Expected behavior

When using a type in parentheses, the function metadata should be able to be generated correctly. This is specifically needed for arrays.

Current behavior

When I run the metadata tool, it returns an error:

Type doesn't match mappings (6, 23)
Type doesn't match mappings (4,14)

Steps to Reproduce

Create a custom function file with the following definition:

/**
 * Do the thing
 * @customfunction
 * @returns {(string | number)[]} The result
 */
export function foo(): (string | number)[] {
  return [];
}

Run the metadata tool against the above file.

However, this also occurs for essentially any type wrapped in parentheses. For example, this code (although silly) also demonstrates the same issue:

/**
 * Do the thing
 * @customfunction
 * @returns {(string)} The result
 */
export function foo(): (string) {
  return [];
}

Diagnosis

The specific issue occurs here:

https://github.com/OfficeDev/Office-Addin-Scripts/blob/e26c633d61d3a5ecdbd3b8cc7d47b90bf4d56292/packages/custom-functions-metadata/src/parseTree.ts#L1311

Where the type of the expression for the array is ParenthesizedType. A naive fix would be something like:

node = arrayType.node;
if (node.kind=== ts.SyntaxKind.ParenthesizedType) {
  node = node.type;
}

However since it also impacts non array types, perhaps it can try and unwrap the type at the end:

node = unwrapNode(node);
type = TYPE_MAPPINGS[node.kind];
if (!type) {
  extra.errors.push(logError("Type doesn't match mappings", typePosition));
}

// This could be extended to account for other weirdness
const unwrapNode = (node: TypeNode): TypeNode => {
  let curr = node;
  while (curr.kind === ts.SyntaxKind.ParenthesizedType) {
    curr = (curr as ParenthesizedTypeNode).type;
  }
  return curr;
};

Context

• Operating System: Win 11
• Node version: 20.14.0
• Typescript: 5.8.3
• Office version: N/A
• Tool version: 2.1.2

Reproduce the metadata-tool failure with the custom function examples, then inspect packages/custom-functions-metadata/src/parseTree.ts around line 1311, where ParenthesizedType is reported. The work is done when parenthesized return types, including the array example, generate metadata without type-mismatch errors.