fix tcl lint

Signed-off-by: Jonas Gava <jfgava@precisioninno.com>

Author: jfgava

src/grt/src/GlobalRouter.tcl

@@ -493,14 +493,22 @@ proc estimate_path_resistance { args } {
   set verbose [info exists flags(-verbose)]
 
   if { [info exists keys(-layer1)] && [info exists keys(-layer2)] } {   
+    set layer1_name $keys(-layer1)
+    set layer2_name $keys(-layer2)
+
     set tech [ord::get_db_tech]
-    set layer1 [$tech findLayer $keys(-layer1)]
+    if { [info exists layer1_name] } {
+      set layer1 [$tech findLayer $layer1_name]
+    }
     if { $layer1 == "NULL" } {
-      utl::error GRT 286 "Layer $keys(-layer1) not found."
+      utl::error GRT 286 "Layer $layer1_name not found."
+    }
+
+    if { [info exists layer2_name] } {
+      set layer2 [$tech findLayer $layer2_name]
     }
-    set layer2 [$tech findLayer $keys(-layer2)]
     if { $layer2 == "NULL" } {
-      utl::error GRT 287 "Layer $keys(-layer2) not found."
+      utl::error GRT 287 "Layer $layer2_name not found."
     }
 
     return [grt::estimate_path_resistance $pin1 $pin2 $layer1 $layer2 $verbose]