No eror shown in rule ediior, if wrong timezone passed to parse_date()

[hc4]

Problem description

I've created rule:

No errors displayed, but on pressing save error shown at the bottom of page:

And REST response contains correct error:
{"type":"ApiError","message":"The datetime zone id '123' is not recognised"}

Environment

• Graylog Version: 2.1.0-beta3
• Pipeline Processor plugin version: 1.1.0-beta.3

[kroepke]

Yes, there's a missing parse error handler for constant arguments at

graylog-plugin-pipeline-processor/src/main/java/org/graylog/plugins/pipelineprocessor/parser/PipelineRuleParser.java

Line 360 in 5cd12d6

final FunctionExpression expr = new FunctionExpression(

[kroepke]

[kroepke]

I've added a proper error message for this class of errors and improved the timezone handling a bit (by allowing arbitrary casing for the timezone name, had to be uppercase before).