♻️ Return number from NumValidator#ensure_* methods

This can simplify some calling code.

Author: nevans

lib/net/imap/data_encoding.rb

@@ -186,23 +186,23 @@ def valid_mod_sequence_value?(num)
 
       # Ensure argument is 'number' or raise DataFormatError
       def ensure_number(num)
-        return if valid_number?(num)
+        return num if valid_number?(num)
 
         msg = "number must be unsigned 32-bit integer: #{num}"
         raise DataFormatError, msg
       end
 
       # Ensure argument is 'nz_number' or raise DataFormatError
       def ensure_nz_number(num)
-        return if valid_nz_number?(num)
+        return num if valid_nz_number?(num)
 
         msg = "nz_number must be non-zero unsigned 32-bit integer: #{num}"
         raise DataFormatError, msg
       end
 
       # Ensure argument is 'mod_sequence_value' or raise DataFormatError
       def ensure_mod_sequence_value(num)
-        return if valid_mod_sequence_value?(num)
+        return num if valid_mod_sequence_value?(num)
 
         msg = "mod_sequence_value must be unsigned 64-bit integer: #{num}"
         raise DataFormatError, msg

lib/net/imap/sequence_set.rb

@@ -1406,12 +1406,11 @@ def range_gte_to(num)
       end
 
       def nz_number(num)
-        case num
-        when Integer, /\A[1-9]\d*\z/ then num = Integer(num)
-        else raise DataFormatError, "%p is not a valid nz-number" % [num]
-        end
-        NumValidator.ensure_nz_number(num)
-        num
+        String === num && !/\A[1-9]\d*\z/.match?(num) and
+          raise DataFormatError, "%p is not a valid nz-number" % [num]
+        NumValidator.ensure_nz_number Integer num
+      rescue TypeError # To catch errors from Integer()
+        raise DataFormatError, $!.message
       end
 
       # intentionally defined after the class implementation