The entire script will fail if, at any point, one of the commands gives an error (or higher) message. Almost all of the SQL used to define objects (DDL) allows a way to avoid throwing errors. More precisely, commands that begin with the DROP keyword have an IF EXISTS option. This allows you to execute the DROP keyword, whether or not the object already exists.
Thus, by the end of the command, that object will not exist:
DROP VIEW IF EXISTS cust_view;
Similarly, most commands that begin with the CREATE keyword have the optional OR REPLACE suffix. This allows the CREATE statement to overwrite the definition if one already exists, or add the new object if it didn't exist yet, like this:
CREATE OR REPLACE VIEW cust_view AS SELECT ...
