Unable to understand warning "Stand-alone call to function 'get' treated as implicit void cast"

UVM
2

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verror 3764

Message # 3764:
Since the function’s return value is not used, the elaboration process
treats this use as if a void cast has been made on the function call.

This means you called a function as a statement and forgot to check the return value. This is usually a bad programming practice as it probably means you are not catching an error condition.
If you want to throw the return value away, you need to cast it to void. For example

void'(uvm_config_db#(int)::get(arguments));

See section 13.4.1 Return values and void functions of the IEEE 1800-2012 LRM