no-duplicate-case
NOTE: this rule is part of the 
recommended rule set.Enable full set in 
deno.json:{
  "lint": {
    "tags": ["recommended"]
  }
}Enable full set using the Deno CLI:
deno lint --tags=recommended
Disallows using the same case clause in a switch statement more than once.
When you reuse a case test expression in a switch statement, the duplicate
case will never be reached meaning this is almost always a bug.
Invalid:
const someText = "a";
switch (someText) {
  case "a": // (1)
    break;
  case "b":
    break;
  case "a": // duplicate of (1)
    break;
  default:
    break;
}
Valid:
const someText = "a";
switch (someText) {
  case "a":
    break;
  case "b":
    break;
  case "c":
    break;
  default:
    break;
}