These checks allows for:
a) `x := call() or { 'abc' }`
b) `x := call() or { panic('abc') }`
c) `x := call() or { exit(123) }`
d) `x := call() or { continue }`
e) `x := call() or { break }`
f) `x := call() or { return }`
... but produce errors for:
g) `x := call() or { println('an error') }` , etc.