fix: LIKE expression with invalid string literals returns a parse error instead of panicking

[Cali0707]

Fixes #931

When visiting the nodes of the AST while parsing the LIKE expression, it looks like we assumed that we would have a valid string literal. However, it is possible that there is no valid string literal, in which case we have to handle that and return an error rather than continuing to parse (and subsequently panicking)

[Cali0707]

cc @duglin @pierDipi @lionelvillard

[duglin]

Aside from my minor question, LGTM

[Cali0707]

cc @embano1

[duglin]

do we have a testcase for this?

[Cali0707]

do we have a testcase for this?

@duglin yes, the new tck test in this PR runs and passes with this change, but prior to the change it would panic

[lionelvillard]

@duglin for final approval/merge

[duglin]

LGTM - it needed a rebase so kicked that off...

[duglin]

merging...