E0198: unexpected statement before first switch case, expected 'case' or 'default'

switch statements contain zero or more labelled statements. It is a syntax error to write a statement inside a switch's body before the first label:

function colorToHexCode(color) {
  switch (color) {
    throw new Error(`unknown color ${color}`);
    case 'red':   return '#ff0000';
    case 'green': return '#00ff00';
    case 'blue':  return '#0000ff';
  }
}

switch (isEven(n)) {
  console.log(`${n} is even`);
}

To fix this error, write a default or case label at the beginning of the switch:

function colorToHexCode(color) {
  switch (color) {
    default:
      throw new Error(`unknown color ${color}`);
    case 'red':   return '#ff0000';
    case 'green': return '#00ff00';
    case 'blue':  return '#0000ff';
  }
}

Alternatively, replace switch with if:

if (isEven(n)) {
  console.log(`${n} is even`);
}

Introduced in quick-lint-js version 2.3.0.

Documentation for other errors