See ZBX-10784 for initial report.

Steps to reproduce:

1. Create host "Testing"
2. Create item:
   • Name: "Trapper"
   • Type: Zabbix Trapper
   • Key: float.trapper
   • Type of information: Numeric (float)
3. Execute

   $ src/zabbix_sender/zabbix_sender -z localhost -s Testing -k float.trapper -o ' "+ "+ + + -3.0  "   " '
   

Result:
Value is accepted:

info from server: "processed: 1; failed: 0; total: 1; seconds spent: 0.001196"
sent: 1; skipped: 0; total: 1

Expected:
"+ "+ + + -3.0 " " is by no means a valid decimal number and item should become not supported.