Add error handling for JSON parsing in facilitator API calls

[voidfuck]

Problem

When the facilitator service returns non-JSON responses (such as HTML error pages, plain text, or malformed JSON), the application crashes with unclear error messages like Unexpected token or Unexpected end of JSON input.

This makes it difficult for developers to debug integration issues, especially when the facilitator server is experiencing errors or returning unexpected content types.

Solution

Added try-catch blocks around all res.json() calls in the useFacilitator functions:

• verify()
• settle()
• supported()
• list()

These blocks provide descriptive error messages that include:

• The operation that failed (verify/settle/supported/list)
• The original error message
• The HTTP status code for context

Example

Before:

SyntaxError: Unexpected token at position 0

After:

Error: Failed to parse verify response as JSON: Unexpected token at position 0. Response status: 200

Impact

• Better debugging experience for developers
• More resilient to unexpected server responses
• Follows error handling best practices
• No breaking changes to the API