build: fix some small errors

These were found by an LLM. None are severe, but to minimize the chances
of unexpected errors or avoid further confusion we address them.

Epic: none
Release note: None

Author: rickystewart

build/bazelbuilder/Dockerfile

@@ -89,10 +89,11 @@ RUN if [[ ${TARGETPLATFORM} != "linux/s390x" ]]; then \
 # NB: As above, this is not available on `s390x`.
 RUN if [[ ${TARGETPLATFORM} != "linux/s390x" ]]; then \
  case ${TARGETPLATFORM} in \
-     "linux/amd64") ARCH=x86_64; SHASUM= ;; \
+     "linux/amd64") ARCH=x86_64; SHASUM=8ba7e746ca05f225e5a73952bbc03f4086a5f65fd94f3717df6f75f212587159 ;; \
      "linux/arm64") ARCH=arm; SHASUM=e6153461e3154ebce61d35b73005bdd14a0ecacd42e5008f66e25b4ad231e5c9 ;; \
  esac  \
  && curl -fsSL "https://dl.google.com/dl/cloudsdk/channels/rapid/downloads/google-cloud-cli-linux-$ARCH.tar.gz" -o gcloud.tar.gz \
+ && echo "$SHASUM gcloud.tar.gz" | sha256sum -c - \
  && tar -xzf gcloud.tar.gz \
  && rm gcloud.tar.gz ; \
  fi

pkg/cmd/bazci/bazci.go

@@ -320,6 +320,9 @@ func sendBepDataToBeaverHub(bepFilepath string) error {
 }
 
 func bazciImpl(cmd *cobra.Command, args []string) error {
+	if len(args) == 0 {
+		return errors.Newf("must provide some subcommand (`build`, `run`, `test`, `coverage`, `merge-test-xmls`, or `munge-test-xml`)")
+	}
 	if args[0] != buildSubcmd && args[0] != runSubcmd && args[0] != coverageSubcmd &&
 		args[0] != testSubcmd && args[0] != mungeTestXMLSubcmd && args[0] != mergeTestXMLsSubcmd {
 		return errors.Newf("First argument must be `build`, `run`, `test`, `coverage`, `merge-test-xmls`, or `munge-test-xml`; got %v", args[0])