private RegisterSpecSet getStarts0(int label) {
    try {
      return blockStarts[label];
    } catch (ArrayIndexOutOfBoundsException ex) {
      // Translate the exception.
      throw new IllegalArgumentException("bogus label");
    }
  }
Helper method, to get the starts for a label, throwing the right exception for range problems.

@param label {@code >= 0;} the block label
@return {@code null-ok;} associated register set or {@code null} if there is none
android/android_framework/dex-maker/src/main/java/com/android/dx/rop/code/LocalVariableInfo.java