adi_project:adi_project_run: Check if $num_reg exist

projects/scripts/adi_project.tcl

@@ -249,10 +249,14 @@ proc adi_project_run {project_name} {
   # Look for undefined clocks which do not show up in the timing summary
   set timing_check [check_timing -override_defaults no_clock -no_header -return_string]
   if {[regexp { (\d+) register} $timing_check -> num_regs]} {
+
+    if {[info exist num_regs]} {
       if {$num_regs > 0} {
         puts "CRITICAL WARNING: There are $num_regs registers with no clocks !!! See no_clock.log for details."
         check_timing -override_defaults no_clock -verbose -file no_clock.log
       }
+    }
+
   } else {
     puts "CRITICAL WARNING: The search for undefined clocks failed !!!"
   }