Controller unhandled errors should be passed as BadStatus to intercep…

…tors

While using `Gruf::Interceptors::Instrumentation::RequestLogging::Interceptor`, I noticed that in the event of of unhandled errors raised in my controller (errors that are not of type `GRPC::BadStatus` or raised via `fail!`), I was not getting any request logging in my log.

In a successful controller call I would get something like:

```
[GRPC::Ok] (list_units) [5.24ms] [GRPC::Ok] (rpc.units.list_units) Parameters: {:is_active=>false, :check_can_delete=>false}
```

If an unhandled error was raised I would get nothing.

My assumption is that I should still get logging in that case. Request info is useful to have, including when an unhandled error occurs.

Investingating why I wasn't getting any, I observed that in `Gruf::Interceptors::Instrumentation::RequestLogging::Interceptor`, the interceptor yields to the controller via this line:

```ruby
result = Gruf::Interceptors::Timer.time(&block)
```

`Gruf::Interceptors::Timer.time` knows to `rescue` and handle errors, but only of type `GRPC::BadStatus`. I realized that unhandled errors would not be caught by it, hence the error logging interceptor would get exited right there and never log.

I noticed that the base controller code turns unhandled errors in the `GRPC::BadStatus` errors. But it only does so after all the interceptors have run (or been tripped as above). I thought why not just do this before the interceptors. Seeing how the logging interceptor is designed, maybe it was even meant to be that way. So this is what I propose here.

It works well for me so far.

API changes:

* Now interceptors will get a `GRPC::BadStatus` error in the case of unhandled errors, instead of the original unhandled error. To reach the original error, `GRPC::BadStatus#cause` can be used.

CHANGELOG.md

@@ -3,6 +3,18 @@ Changelog for the gruf gem. This includes internal history before the gem was ma
 ### Pending release
 
 * [#190] Remove unsued `e2mmap` and `thwait` gems from `runtime_dependency`.
+* [#184] [Breaking] Controller unhandled errors should be passed as BadStatus to interceptors.
+  * Server interceptors should now expect a `GRPC::BadStatus` error in the case of unhandled errors.
+    Orignal unhandled error can be reached via `cause`. example:
+    ```ruby
+    def call
+      begin
+        yield
+      rescue => err
+        err.cause
+      end
+    end
+    ```
 
 ### 2.19.0
 

lib/gruf/controllers/base.rb

@@ -92,13 +92,13 @@ def process_action(method_key, &block)
       def call(method_key, &block)
         Interceptors::Context.new(@interceptors).intercept! do
           process_action(method_key, &block)
+        rescue GRPC::BadStatus
+          raise # passthrough, to be caught by Gruf::Interceptors::Timer
+        rescue GRPC::Core::CallError, StandardError => e # CallError is not a StandardError
+          set_debug_info(e.message, e.backtrace) if Gruf.backtrace_on_error
+          error_message = Gruf.use_exception_message ? e.message : Gruf.internal_error_message
+          fail!(:internal, :unknown, error_message)
         end
-      rescue GRPC::BadStatus
-        raise # passthrough, to be caught by Gruf::Interceptors::Timer
-      rescue GRPC::Core::CallError, StandardError => e # CallError is not a StandardError
-        set_debug_info(e.message, e.backtrace) if Gruf.backtrace_on_error
-        error_message = Gruf.use_exception_message ? e.message : Gruf.internal_error_message
-        fail!(:internal, :unknown, error_message)
       end
     end
   end

spec/gruf/controllers/base_spec.rb

@@ -97,6 +97,16 @@
         end
       end
 
+      it 'raises a GRPC::Internal error to interceptors' do
+        Gruf.interceptors.use(TestServerInterceptor)
+        expect_any_instance_of(TestServerInterceptor).to receive(:call) do |&block|
+          error = nil
+          expect { block.call }.to raise_error(GRPC::Internal) { |err| error = err }
+          raise error if error
+        end
+        expect { subject }.to raise_error(GRPC::Internal)
+      end
+
       context 'when backtrace_on_error is set to true' do
         before do
           Gruf.backtrace_on_error = true