TypeError: 'NoneType' object is not callable in mcp-proxy during browser navigation (ADK/MCP Parallel Setup)

I am encountering a TypeError: 'NoneType' object is not callable in the mcp-proxy terminal when attempting to execute browser automation tests using google.adk's MCPToolset for parallel test suite execution. Although the browser instances launch (displaying "about:blank" tabs), navigation to the specified URL fails due to this internal proxy error.