rubocop: fix offences of the Lint/ReturnInVoidContext cop

.rubocop_todo.yml

@@ -13,11 +13,6 @@ Gemspec/RequiredRubyVersion:
   Exclude:
     - 'pry.gemspec'
 
-# Offense count: 1
-Lint/ReturnInVoidContext:
-  Exclude:
-    - 'lib/pry/command_set.rb'
-
 # Offense count: 1
 Lint/ShadowedException:
   Exclude:

lib/pry/command_set.rb

@@ -325,7 +325,11 @@ class Pry
     #   Pry.config.commands["help"] = MyHelpCommand
     #
     def []=(pattern, command)
-      return @commands.delete(pattern) if command.equal?(nil)
+      if command.equal?(nil)
+        @commands.delete(pattern)
+        return
+      end
+
       unless Class === command && command < Pry::Command
         raise TypeError, "command is not a subclass of Pry::Command"
       end