channel: recognized nvim-style errors

2 files changed, 25 insertions, 1 deletions

diff --git a/src/nvim/msgpack_rpc/channel.c b/src/nvim/msgpack_rpc/channel.c
index 9c812ced82..b671b8b545 100644
--- a/src/nvim/msgpack_rpc/channel.c
+++ b/src/nvim/msgpack_rpc/channel.c
@@ -225,7 +225,25 @@ Object channel_send_call(uint64_t id,
   channel->pending_requests--;
 
   if (frame.errored) {
-    api_set_error(err, Exception, "%s", frame.result.data.string.data);
+    if (frame.result.type == kObjectTypeString) {
+      api_set_error(err, Exception, "%s", frame.result.data.string.data);
+    } else if (frame.result.type == kObjectTypeArray) {
+      // Should be an error in the form [type, message]
+      Array array = frame.result.data.array;
+      if (array.size == 2 && array.items[0].type == kObjectTypeInteger
+          && (array.items[0].data.integer == kErrorTypeException
+              || array.items[0].data.integer == kErrorTypeValidation)
+          && array.items[1].type == kObjectTypeString) {
+        err->type = (ErrorType) array.items[0].data.integer;
+        xstrlcpy(err->msg, array.items[1].data.string.data, sizeof(err->msg));
+        err->set = true;
+      } else {
+        api_set_error(err, Exception, "%s", "unknown error");
+      }
+    } else {
+      api_set_error(err, Exception, "%s", "unknown error");
+    }
+
     api_free_object(frame.result);
   }
 
diff --git a/test/functional/api/server_requests_spec.lua b/test/functional/api/server_requests_spec.lua
index a53fd8e006..34669c5f29 100644
--- a/test/functional/api/server_requests_spec.lua
+++ b/test/functional/api/server_requests_spec.lua
@@ -148,5 +148,11 @@ describe('server -> client', function()
       -- Call get_line_slice(buf, range [0,0], includes start, includes end)
       eq({'SOME TEXT'}, eval("rpcrequest(vim, 'buffer_get_line_slice', "..buf..", 0, 0, 1, 1)"))
     end)
+
+    it('returns an error if the request failed', function()
+      local status, err = pcall(eval, "rpcrequest(vim, 'does-not-exist')")
+      eq(false, status)
+      eq(true, string.match(err, ': (.*)') == 'Failed to evaluate expression')
+    end)
   end)
 end)