Running `yarn deploy` gives `TypeError: Cannot read property 'length' of undefined`

Nobody has claimed this yet.

I am trying to use the instructions [here](https://github.com/livepeer/protocol/blob/confluence/README.md) to deploy the protocol to the Ethereum Ephemery testnet.

Steps to reproduce:

1. clone the protocol repo with:
```
git clone https://github.com/livepeer/protocol.git
```
2. copy the `.env.sample` file to `.env`
3. add a private key, corresponding to an address with funds on Ephemery, to `PRIVATE_KEY=`
4. Add the following in `hardhat.config.ts` under `networks`:
```
ethereumEphemeryDevnet: {
url: `https://eth.ephemeral.zeus.fyi`,
accounts: PRIVATE_KEY ? [`0x${PRIVATE_KEY}`] : undefined
},
```
5. Set the `defaultNetwork` in hardhat.config.ts to `ethereumEphemeryDevnet`.
6. Run the following:
```
yarn
export LPT_DEPLOYMENT_EXPORT_PATH=~/Development/lpt_contracts.json
yarn deploy
```
7. See error:
```
Error: ERROR processing /home/ubuntu/protocol/deploy/deploy_contracts.ts:
TypeError: Cannot read property 'length' of undefined
at getFrom (/home/ubuntu/protocol/node_modules/hardhat-deploy/src/helpers.ts:1642:14)
at _deploy (/home/ubuntu/protocol/node_modules/hardhat-deploy/src/helpers.ts:537:9)
at processTicksAndRejections (internal/process/task_queues.js:97:5)
at async _deployOne (/home/ubuntu/protocol/node_modules/hardhat-deploy/src/helpers.ts:934:16)
at DeploymentsManager.executeDeployScripts (/home/ubuntu/protocol/node_modules/hardhat-deploy/src/DeploymentsManager.ts:1232:19)
at processTicksAndRejections (internal/process/task_queues.js:97:5)
error Command failed with exit code 1.
```

Start with deploy/deploy_contracts.ts and hardhat.config.ts, then run the documented Ephemery setup and yarn deploy to reproduce the failure. Trace the deployment configuration around the reported hardhat-deploy error and verify that deployment completes without the TypeError.

Written by the indexing model from the issue text.