[master < T1039] Fix map at operator returning null from a map

[Josipmrden]

[master < Task] PR

• Check, and update documentation if necessary
• Provide the full content or a guide for the final git message

To keep docs changelog up to date, one more thing to do:

• Write a release note here, including added/changed clauses
  Fixed bug when returning values from a map (now returning null instead of an exception happening)
• Tag someone from docs team in the comments

[Josipmrden]

@vpavicic

[vpavicic]

When no values are returned from a map, a null is returned instead of an
exception occurring.

@Josipmrden ok?