Throw FormatException when Int32/Int64.parseRadix() encounters bad digit

pkg/fixnum/lib/src/int64.dart

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 part of fixnum;
 
 /**
  * An immutable 64-bit signed integer, in the range [-2^63, 2^63 - 1].
  * Arithmetic operations may overflow in order to maintain this range.
  */
@@ skipping 63 matching lines @@
     bool negative = false;
     if (s[0] == '-') {
       negative = true;
       i++;
     }
     int d0 = 0, d1 = 0, d2 = 0;  //  low, middle, high components.
     for (; i < s.length; i++) {
       int c = s.codeUnitAt(i);
       int digit = Int32._decodeDigit(c);
       if (digit < 0 || digit >= radix) {
-        throw new Exception("Non-radix char code: $c");
+        throw new FormatException("Non-radix char code: $c");
       }
 
       // [radix] and [digit] are at most 6 bits, component is 22, so we can
       // multiply and add within 30 bit temporary values.
       d0 = d0 * radix + digit;
       int carry = d0 >> _BITS;
       d0 = _MASK & d0;
 
       d1 = d1 * radix + carry;
       carry = d1 >> _BITS;
@@ skipping 944 matching lines @@
       if (r0 == 0 && r1 == 0 && r2 == 0) {
         return ZERO;
       } else {
         return _sub(b0, b1, b2, r0, r1, r2);
       }
     } else {
       return _negate(r0, r1, r2);
     }
   }
 }