pdn: validate -layers and -cut_pitch arguments in add_sroute_connect

Add missing existence and length checks for required arguments to prevent
downstream errors and improve error messages.

- PDN 1193: error when -layers is missing
- PDN 1194: error when -cut_pitch is missing
- PDN 1195: error when -layers does not have exactly 2 elements
- PDN 1196: error when -cut_pitch does not have exactly 2 values

Signed-off-by: Suhrid Marwah <suhridmarwah07@gmail.com>

Author: suhr25

src/pdn/src/pdn.tcl

@@ -670,6 +670,19 @@ proc add_sroute_connect { args } {
       -metalspaces -ongrid -insts} \
     flags {}
 
+  if { ![info exists keys(-layers)] } {
+    utl::error PDN 1193 "The -layers argument is required."
+  }
+  if { [llength $keys(-layers)] != 2 } {
+    utl::error PDN 1195 "The -layers argument must be a list of 2 layers."
+  }
+  if { ![info exists keys(-cut_pitch)] } {
+    utl::error PDN 1194 "The -cut_pitch argument is required."
+  }
+  if { [llength $keys(-cut_pitch)] != 2 } {
+    utl::error PDN 1196 "The -cut_pitch argument must be a list of 2 pitch values."
+  }
+
   set l0 [pdn::get_layer [lindex $keys(-layers) 0]]
   set l1 [pdn::get_layer [lindex $keys(-layers) 1]]