Tests for error cases with Timeline.setInstruments.


== Running test suite: Timeline.setInstruments.errors
-- Running test case: MissingRequiredArgument
PASS: Should be an error: Some arguments of method 'Timeline.setInstruments' can't be processed

-- Running test case: InvalidTypeInInstrumentsList
PASS: Should be an error: Unexpected non-string value in given instruments

-- Running test case: InvalidInstrumentInInstrumentsList
PASS: Should be an error: Unknown instrument: NoSuchInstrument

-- Running test case: ValidInstrumentInInstrumentsList
PASS: Should not be an error setting valid instruments.