Redundant begin: do not report if there is an inner handler

fixes #56

spec/ameba/rule/redundant_begin_spec.cr

@@ -153,7 +153,7 @@ module Ameba::Rule
       subject.catch(s).should_not be_valid
     end
 
-    it "fails if there is an inner redundant block" do
+    it "doesn't report if there is an inner redundant block" do
       s = Source.new %q(
         def method
           begin
@@ -164,7 +164,7 @@ module Ameba::Rule
         rescue
         end
       )
-      subject.catch(s).should_not be_valid
+      subject.catch(s).should be_valid
     end
 
     it "fails if there is a redundant block with yield" do

src/ameba/rule/redundant_begin.cr

@@ -88,14 +88,18 @@ module Ameba::Rule
     end
 
     private def redundant_begin_in_handler?(source, handler, node)
-      return false if begin_exprs_in_handler?(handler)
+      return false if begin_exprs_in_handler?(handler) || inner_handler?(handler)
 
       code = node_source(node, source.lines).try &.join("\n")
       def_redundant_begin? code if code
     rescue
       false
     end
 
+    private def inner_handler?(handler)
+      handler.body.is_a?(Crystal::ExceptionHandler)
+    end
+
     private def begin_exprs_in_handler?(handler)
       if (body = handler.body).is_a?(Crystal::Expressions)
         exception_handler?(body.expressions.first)