How to avoid RMAN-10015 when using sql-directives in an RMAN script

When attempting to use an sql directive in RMAN, you will sometimes be instructed to use the following syntax:

sql "alter session set events ' '1110 trace name errorstack level 3' '";

This will throw an error upon execution:

RMAN-03009: failure of sql command on default channel at 08/01/2019 11:20:02
RMAN-10015: error compiling PL/SQL program

Solution: do not use white spaces between the single quotes.
This will work:

sql "alter session set events ''1110 trace name errorstack level 3'' ";