See ZBX-10784 for initial report.

Steps to reproduce:

1. Create host "Testing"
2. Create item:
   • Name: "Calculated"
   • Type: Calculated
   • Key: calculated
   • Formula:

     count(float.trapper,#10,+1)

3. Check Zabbix server log file.

Result:

item "Testing:calculated" became not supported: Cannot evaluate expression: "Cannot evaluate function "count(#10,+1)": "+1" is not a valid numeric float value.".

Expected:
"+" sign does not make a number invalid, check test cases in tests/libs/zbxcommon/is_double.yaml