Return semantic error if doc ops range is not loaded

services/real-time/app/coffee/DocumentUpdaterManager.coffee

@@ -23,6 +23,11 @@ module.exports = DocumentUpdaterManager =
 				catch error
 					return callback(error)
 				callback null, body?.lines, body?.version, body?.ops
+			else if res.statusCode == 422 # Unprocessable Entity
+				err = new Error("doc updater could not load requested ops")
+				err.statusCode = res.statusCode
+				logger.warn {err, project_id, doc_id, url, fromVersion}, "doc updater could not load requested ops"
+				callback err
 			else
 				err = new Error("doc updater returned a non-success status code: #{res.statusCode}")
 				err.statusCode = res.statusCode

services/real-time/app/coffee/Router.coffee

@@ -21,8 +21,8 @@ module.exports = Router =
 				attrs[key] = value
 			attrs.client_id = client.id
 			attrs.err = error
-			if error.message == "not authorized"
-				logger.warn attrs, "client is not authorized"
+			if error.message in ["not authorized", "doc updater could not load requested ops"]
+				logger.warn attrs, error.message
 				return callback {message: error.message}
 			else
 				logger.error attrs, "server side error in #{method}"

services/real-time/test/unit/coffee/DocumentUpdaterManagerTests.coffee

@@ -17,7 +17,7 @@ describe 'DocumentUpdaterManager', ->
 			
 		@DocumentUpdaterManager = SandboxedModule.require modulePath, requires:
 			'settings-sharelatex':@settings
-			'logger-sharelatex': @logger = {log: sinon.stub(), error: sinon.stub()}
+			'logger-sharelatex': @logger = {log: sinon.stub(), error: sinon.stub(), warn: sinon.stub()}
 			'request': @request = {}
 			'redis-sharelatex' : createClient: () => @rclient
 
@@ -50,6 +50,18 @@ describe 'DocumentUpdaterManager', ->
 			it "should return an error to the callback", ->
 				@callback.calledWith(@error).should.equal true
 
+		describe "when the document updater returns a 422 status code", ->
+			beforeEach ->
+				@request.get = sinon.stub().callsArgWith(1, null, { statusCode: 422 }, "")
+				@DocumentUpdaterManager.getDocument @project_id, @doc_id, @fromVersion, @callback
+
+			it "should return the callback with an error", ->
+				err = new Error("doc updater could not load requested ops")
+				err.statusCode = 422
+				@callback
+					.calledWith(err)
+					.should.equal true
+
 		describe "when the document updater returns a failure error code", ->
 			beforeEach ->
 				@request.get = sinon.stub().callsArgWith(1, null, { statusCode: 500 }, "")