Improve error handling in wezterm plugins and event handlers

[mrolli]

Is your feature request related to a current shortcoming? Please describe.
Currently, the wezterm configuration lacks error handling when calling plugin functions and event handlers. If a plugin fails or returns unexpected values (e.g., nil), it could cause issues in the status bar rendering.

Describe the solution you'd like

• Add error handling with pcall() around plugin calls
• Handle nil values returned by plugins (e.g., trackinfo on non-Darwin platforms)
• Filter out nil values before building status bar cells
• Add defensive checks in event handlers
• Consider logging errors for debugging

Additional context
This will make the configuration more robust and prevent crashes when plugins encounter errors or unsupported platforms.