Don't use robust "key not found" error when errors are suppressed

The robust error message involves calling "alarm", which will cancel
any alarms we might be trying to catch using "try" or ??.

Closes: Macaulay2#3524

M2/Macaulay2/d/hashtables.dd

@@ -318,10 +318,11 @@ lookup(object:HashTable, key:Expr):Expr; -- forward declaration
 KeyNotFound(object:string, key:Expr):Expr := (
     -- TODO: implement a similar trick to call synonym(object)
     msg := "key not found in " + object;
-    see := lookup(Class(key), RobustPrintE);
-    if see != notfoundE then
-    when applyEEEpointer(see, toExpr(msg), key)
-    is str:stringCell do msg = str.v else nothing;
+    if !SuppressErrors then (
+	see := lookup(Class(key), RobustPrintE);
+	if see != notfoundE then
+	when applyEEEpointer(see, toExpr(msg), key)
+	is str:stringCell do msg = str.v else nothing);
     buildErrorPacket(msg));
 
 export lookup1(object:HashTable,key:Expr,keyhash:hash_t):Expr := (