The terminal in vscode is indicating that system verilog is necessary for $dumpfile and $dumpvars to function properly, as they are currently not working.

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This means that you need to install a SystemVerilog simulator or compiler, such as ModelSim or Verilator, in order to use these features in your code. Once you have installed a suitable tool, you should be able to generate a VCD file using $dumpfile and $dumpvars. Be sure to verify that your simulator or compiler supports these commands, and consult its documentation for guidance on using them correctly.