Non deterministic behaviour for Constant Throughput Timer and wrongly set value (via variable)

**piotr.mirek** ([Bug 64928](https://bz.apache.org/bugzilla//show_bug.cgi?id=64928&redirect=false)):
Component impacted:

* Constant Throughput Timer

Case:

* value of target throughput set to: ${__P(tpm)} (or any other variable/property)
* tpm value is not a valid positive float number (e.g. tpm is set to 'thing' or to '-1' or even not set at all)

Currently there is no validation against given value when the test runs. No error is presented to the user and it's not easy to pinpoint the issue.

Solution:

There should be a check against the value of the variable when value of the variable/property is assigned to mentioned component, to make sure that the value is positive float number or similar.

Severity: normal
OS: All