Repl Allows One Command to Execute and Subsequent Commands Fail

Description

When I use the repl, I can run one command and that's it. After that I get an error.

Steps to reproduce the issue:

1. run repl
2. run 2 + 2 (works)
3. run 2 + 1 (error)

Received results:

cayley> 2 + 2

=> 4
-----------
1 Result
Elapsed time: 1.95 ms

cayley> 2+1

Error:  iterator closed at <eval>:1:1(0)
cayley> 

Expected results:

It should allow me to run multiple commands

Output of cayley version or commit hash:

ERROR: logging before flag.Parse: E1014 21:20:53.997357   97410 cayley.go:142] The assets flag is deprecated as assets are provided as part of the binary.
Cayley version: 0.7.7
Git commit hash: dcf764f

Environment details:

Backend database: bolt version unknown