Unexpected token U in JSON at position 0 is a very common error that happens in JavaScript due to JSON.parse trying to parse an undefined value, always try-catch JSON.parse.

parseJsonAndLogIfError.ts

// Unexpected token U in JSON at position 0 is a very common error that happens in JavaScript due to JSON.parse trying to parse an undefined value, always try-catch JSON.parse. 

export function parseJsonAndLogIfError(
  data: string,
  context: string,
): unknown {
  try {
    return JSON.parse(data);
  } catch (e) {
    Bugsnag.notify(`Tried to JSON parse invalid value: ${data} in ${context}`);
  }
}