Add DBC REQUIRE to check that 'text' is non NULL
requested to merge 2703-gcc-10-fanalyzer-reports-dereference-of-null-text-in-server-c-14721-v9_16 into v9_16
for all control channel commands. This should silence gcc-10-analyzer reporting NULL pointer dereference of 'text'.
(cherry picked from commit ac0fc3c2)
Closes #2703 (closed)