Improve error messaging

## Current behavior
```
An error occurred while attempting to convert '['/var/folders/_0/hsvm3gjx1q7br2grg3gx901c0000gn/T/OdkChoicesError.xlsx']': List 'yes_no_list' not found.
```

## Desired behavior
```
An error occurred while attempting to convert 'OdkChoicesError.xlsx'.
OdkChoicesError: List 'yes_no_list' not found.
```