Add error handling for fetch request in loadTaggings

[Copilot]

Addresses missing error handling in the loadTaggings method that fetches CSV data from the google/fonts repository. Without proper error handling, network failures or HTTP errors would silently fail.

Changes

• Check response.ok before processing response text
• Throw descriptive error with HTTP status on failed requests
• Add .catch() block to log fetch and processing errors

fetch(tagsUrl)
  .then((response) => {
    if (!response.ok) {
      throw new Error(`Failed to fetch tags: ${response.status} ${response.statusText}`);
    }
    return response.text();
  })
  .then((csvText) => {
    // Process CSV...
  })
  .catch((error) => {
    console.error("Error loading taggings from CSV:", error);
  });

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