allow rescue from non-StandardError exceptions to use default error handling

Author: Jelkster

CHANGELOG.md

@@ -11,6 +11,7 @@
 * [#1749](https://github.com/ruby-grape/grape/pull/1749): Allow rescue from non-`StandardError` exceptions - [@dm1try](https://github.com/dm1try).
 * [#1750](https://github.com/ruby-grape/grape/pull/1750): Fix a circular dependency warning due to router being loaded by API - [@salasrod](https://github.com/salasrod).
 * [#1752](https://github.com/ruby-grape/grape/pull/1752): Fix `include_missing` behavior for aliased parameters - [@jonasoberschweiber](https://github.com/jonasoberschweiber).
+* [#1754](https://github.com/ruby-grape/grape/pull/1754): Allow rescue from non-`StandardError` exceptions to use default error handling - [@jelkster](https://github.com/jelkster).
 * Your contribution here.
 
 ### 1.0.2 (1/10/2018)

README.md

@@ -2289,7 +2289,7 @@ Here `'inner'` will be result of handling occured `ArgumentError`.
 
 Any exception that is not subclass of `StandardError` should be rescued explicitly.
 Usually it is not a case for an application logic as such errors point to problems in Ruby runtime.
-This is following [standard recomendations for exceptions handling](https://ruby-doc.org/core/Exception.html).
+This is following [standard recommendations for exceptions handling](https://ruby-doc.org/core/Exception.html).
 
 ### Rails 3.x
 

lib/grape/middleware/error.rb

@@ -36,7 +36,7 @@ def call!(env)
           error_response(catch(:error) do
             return @app.call(@env)
           end)
-        rescue StandardError => e
+        rescue Exception => e # rubocop:disable Lint/RescueException
           is_rescuable = rescuable?(e.class)
           if e.is_a?(Grape::Exceptions::Base) && (!is_rescuable || rescuable_by_grape?(e.class))
             handler = ->(arg) { error_response(arg) }
@@ -46,14 +46,6 @@ def call!(env)
           end
 
           handler.nil? ? handle_error(e) : exec_handler(e, &handler)
-        rescue Exception => e # rubocop:disable Lint/RescueException
-          handler = options[:rescue_handlers].find do |error_class, error_handler|
-            break error_handler if e.class <= error_class
-          end
-
-          raise unless handler
-
-          exec_handler(e, &handler)
         end
       end
 
@@ -72,7 +64,12 @@ def find_handler(klass)
 
       def rescuable?(klass)
         return false if klass == Grape::Exceptions::InvalidVersionHeader
-        rescue_all? || rescue_class_or_its_ancestor?(klass) || rescue_with_base_only_handler?(klass)
+
+        if klass <= StandardError
+          rescue_all? || rescue_class_or_its_ancestor?(klass) || rescue_with_base_only_handler?(klass)
+        else
+          rescue_class_or_its_ancestor?(klass) || rescue_with_base_only_handler?(klass)
+        end
       end
 
       def rescuable_by_grape?(klass)

spec/grape/middleware/exception_spec.rb

@@ -110,18 +110,35 @@ def app
   end
 
   context 'Non-StandardError exception with a provided rescue handler' do
-    subject do
-      Rack::Builder.app do
-        use Spec::Support::EndpointFaker
-        use Grape::Middleware::Error, rescue_handlers: { NotImplementedError => -> { [200, {}, 'rescued'] } }
-        run ExceptionSpec::OtherExceptionApp
+    context 'default error response' do
+      subject do
+        Rack::Builder.app do
+          use Spec::Support::EndpointFaker
+          use Grape::Middleware::Error, rescue_handlers: { NotImplementedError => nil }
+          run ExceptionSpec::OtherExceptionApp
+        end
+      end
+      it 'rescues the exception using the default handler' do
+        get '/'
+        expect(last_response.body).to eq('snow!')
       end
     end
-    it 'rescues the exception using the provided handler' do
-      get '/'
-      expect(last_response.body).to eq('rescued')
+
+    context 'custom error response' do
+      subject do
+        Rack::Builder.app do
+          use Spec::Support::EndpointFaker
+          use Grape::Middleware::Error, rescue_handlers: { NotImplementedError => -> { [200, {}, 'rescued'] } }
+          run ExceptionSpec::OtherExceptionApp
+        end
+      end
+      it 'rescues the exception using the provided handler' do
+        get '/'
+        expect(last_response.body).to eq('rescued')
+      end
     end
   end
+
   context do
     subject do
       Rack::Builder.app do