Fix Shellcheck SC2154: variable possibly undefined
Fix Shellcheck SC2154: variable possibly undefined

var is referenced but not assigned.

https://github.com/koalaman/shellcheck/wiki/SC2154

Signed-off-by: Dan Callahan <b611df31359e9ab1bf729fd0aaebf4ab4b2ecf3e@element.io>

matrix-org/synapse,matrix-org/synapse,matrix-org/synapse,matrix-org/synapse,matrix-org/synapse,matrix-org/synapse