posint get_value() : ignore invalid digits

lib-nested-core/src/editors/integer/mod.rs

@@ -35,9 +35,11 @@ pub trait PositionalUInt : SequenceView<Item = u64> {
         let mut val = 0;
         let mut r = 1;
         for i in 0..self.len().unwrap_or(0) {
-            val += r * self.get(&i).unwrap();
+            if let Some(digit_val) = self.get(&i) {
+                val += r * digit_val;
                 r *= self.get_radix();
             }
+        }
 
         val  
     }