Repl Allows One Command to Execute and Subsequent Commands Fail

[joshglenn]

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

[catundercar]

I found the problem:

1. When run a command, the session of gizmo will new a iterator. After the first command done, the iterator will be closed.
2. The problem occurs at the time of closing iterator：
   
   
   It will make the vm be interrupted.
   3.Then run the second command, the vm will check interrupted.
   
   So, panic.

Temporary Solutions：

cayley/query/gizmo/gizmo.go

Line 326 in 94f1b49

it.s.vm.Interrupt(err)