Problem description: in case if the "Regular expression" preprocessing step is used, and the pattern that is provided in the 1st parameter did not match the value received by the item, the displayed error message contains wrong data type ("none" instead of "sting"). Furthermore, the message starts with a non-capital letter in case of it is observed in Item test dialog, which is not consistant with 99% of error messages in Zabbix:

Steps to reproduce:

1. Create an item with key "agent.version"
2. Open preprocessing tab
3. Add preprocessing step "Regular expression" with the first parameter that will not match with the current zabbix agent version
4. Press "Test" button
5. In the opened "Item test" dialog press "Get value and test" button.

Result: the error starts with a non-capital letter and mentions wrong data type, which may be highly misleading for the end user (type "none" instead of "string")
Expected:
1 - the error message should start with a Capital letter.
2 - the error mesage should mention the correct data type (in this case "string").