Firestore [ReferenceError: Can't find variable: xxx]

Question

I am trying to update a nested collection in Firebase with my Expo React-Native app and I am receiving an error from a catch statement:

Error updating user activities map: [ReferenceError: Can't find variable: activities]

This is interesting as the function works normally and the Firestore collection still updates, however this error is logged regardless. The issue here is that my dispatch in the .then() statement is never reached as the .catch() always occurs.

I believe this is due to the firestore.collection('users').doc(userId).collection('activities').doc(activityId).set() catch statement. I am confused because the activities collection exists and is written to in the function, and even if it does not exist, I recall reading somewhere that Firestore will automatically create the document. Can someone please provide me some assistance with this error?

DB structure: users (collection) -> [some user id] (document) -> activities (collection) -> [some activity document]

const activityRef = firestore.collection('activities').doc(activityId);

let activityInfo = {}
let participants = {}

// get activity information
activityRef.get()
.then(doc => {
    activityInfo = doc.data();
    participants = doc.data().participants;
})
.then(() => {
    // update participant activity status 
    participants[userId] = 'participant';
    
    // update activityRef with new participant
    activityRef.update({ participants }).then(() => {
        // add to activities collection in the current user document
        firestore.collection('users').doc(userId).collection('activities').doc(activityId)
        .set({
            id: activityId,
            status: 'participant'
        })
        .then(() => {
            console.log('activity info', activityInfo);
            dispatch({
                type: 'ENROLL_ACTIVITY',
                activityId,
                activity: activityInfo
            });
        })
        .catch((error) => {
            console.log('catch statement: activityInfo', activityInfo);
            // The document probably doesn't exist.
            console.log("Error updating user activities map: ", error);
        })
   })
   .catch(error => {
        // The document probably doesn't exist.
        console.error("Error updating activity document: ", error);
   });
})

Thank you for reading this! Any information would be helpful in trying to resolve this error :)

EDIT: If I remove the catch statement

.catch((error) => {
            console.log('catch statement: activityInfo', activityInfo);
            // The document probably doesn't exist.
            console.log("Error updating user activities map: ", error);
        })

then I get this yellow warning unhandled promise rejection, does this error look familiar to anyone?

[Unhandled promise rejection: ReferenceError: Can't find variable: activities]

Stack trace:
  node_modules/immer/dist/immer.module.js:39:2 in assignMap
  node_modules/redux/lib/redux.js:464:32 in combination
  node_modules/redux/lib/redux.js:218:6 in dispatch
  node_modules/promise/setimmediate/core.js:37:13 in tryCallOne
  node_modules/promise/setimmediate/core.js:123:24 in setImmediate$argument_0
  node_modules/react-native/Libraries/Core/Timers/JSTimers.js:135:14 in _callTimer
  node_modules/react-native/Libraries/Core/Timers/JSTimers.js:183:16 in _callImmediatesPass
  node_modules/react-native/Libraries/Core/Timers/JSTimers.js:446:30 in callImmediates
  [native code]:null in callImmediates
  node_modules/react-native/Libraries/BatchedBridge/MessageQueue.js:396:6 in __callImmediates
  node_modules/react-native/Libraries/BatchedBridge/MessageQueue.js:144:6 in __guard$argument_0
  node_modules/react-native/Libraries/BatchedBridge/MessageQueue.js:373:10 in __guard
  node_modules/react-native/Libraries/BatchedBridge/MessageQueue.js:143:4 in flushedQueue
  [native code]:null in flushedQueue
  [native code]:null in callFunctionReturnFlushedQueue
  ...