Catch null values and function calls

[philippkahr]

Based on e.g. elastic/integrations#8670 but when you do:

if: ctx.cool.field.startsWith('abc')

or anythign really that uses a function like startsWith(),contains(),… it won’t work if it is null and you get a painless error along the lines of null does not have function `startsWith()``

Would it be possible to test this? To make sure that this is captured as it should at least look like this:

if: ctx.cool?.field?.startsWith('abc') ?: false

because that surpresses the error at least and the other processors work as intended (hopefully).

Best should be:

if: ctx.cool?.field instanceof String && ctx.cool.field.startsWith('abc')

At least that we can highlight when somebody is using startsWith(), contains() and those thinks, inside the if clause on a processor level to ensure that they don’t break something?