Add missing catch statements in BigQuery samples.
Add missing catch statements in BigQuery samples.

GoogleCloudPlatform/nodejs-docs-samples,GoogleCloudPlatform/nodejs-docs-samples,JustinBeckwith/nodejs-docs-samples,JustinBeckwith/nodejs-docs-samples,thesandlord/nodejs-docs-samples,GoogleCloudPlatform/nodejs-docs-samples,JustinBeckwith/nodejs-docs-samples,GoogleCloudPlatform/nodejs-docs-samples,thesandlord/nodejs-docs-samples