fixed a crash due to not using PIU in fieldval_uniq_rand

fieldpattern.cpp

@@ -30,7 +30,7 @@ struct fgeomextra {
 extern int subpathid;
 extern int subpathorder;
 
-#define MWDIM (WDIM+1)
+#define MWDIM (prod ? 3 : WDIM+1)
 
 bool isprime(int n) {
   for(int k=2; k<n; k++) if(n%k == 0) return false;

pattern2.cpp

@@ -409,6 +409,12 @@ EX int fieldval_uniq(cell *c) {
   }
 
 EX int fieldval_uniq_rand(cell *c, int randval) {
+  if(prod) { 
+    auto c1 = product::get_where(c).first; 
+    int res;
+    product::in_underlying_map([&] { res = fieldval_uniq_rand(c1, randval); });
+    return res; 
+    }
   if(sphere || euclid || NONSTDVAR) 
     // we do not care in these cases
     return fieldval_uniq(c);