Exception in tutorial causes improper control flow

[edwfeng]

Describe the bug
The tutorial relies on the user inputting the keyword next for moving between different sections. However, when an exception is raised, the next keyword needs to be input twice to continue.

To Reproduce

• What steps should be executed to reproduce the bug?
  • Follow the tutorial to the end of the "substitute all" section
  • Run eval b x=1, which succeeds, causing the tutorial to print "Continue testing this feature, or type 'next' to continue."
  • Run eval b a=1, which throws a java.util.NoSuchElementException
  • Type the next keyword—this simply prints out a >>> prompt rather than continuing to the next section
• Which interface are you using? commandui
• What constants and functions are defined in the current session? N/A
• What settings are enabled in the config, and are any changed manually during the session? N/A

Expected behavior
The tutorial only requires one next to continue to the next section.

Screenshots

The definition of b, for reference

Expected behavior, only requires one next

Actually requires two nexts

Version
master, commit 28957a4

Additional context
This bug is a possible indication that other input-related errors may exist.

[eiis1000]

Thanks for the issue, we'll get to it eventually :)