Fix UI build.

Author: brocaar

Makefile

@@ -8,5 +8,5 @@ nix-start:
 	cd interface && cargo run
 
 nix-test:
-	cd interface/ui && yarn build
+	cd interface && make api ui
 	cd interface && cargo run run-tests

interface/Makefile

@@ -10,4 +10,4 @@ api:
 	$(PROTOC_PATH) $(PROTOC_ARGS) api/api.proto
 
 ui:
-	cd ui && yarn add file:./api/grpc-web && yarn install
+	cd ui && yarn add file:./api/grpc-web && yarn install && yarn build