+++ This bug was initially created as a clone of Bug #1849556 +++

Description of problem:
console hit runtime error when all receivers are deleted

Version-Release number of selected component (if applicable):
4.5.0-0.nightly-2020-06-20-194346

How reproducible:
Always

Steps to Reproduce:
1. goto monitoring/alertmanageryaml page, and delete all receivers including Critical, Default and Watchdog
2. refresh the page
3.

Actual results:
2. got the blank and hit runtime error:
Uncaught TypeError: Cannot read property 'filter' of undefined
    at main-chunk-b5f4dd3fa1772b07e0e5.min.js:1
    at W (main-chunk-b5f4dd3fa1772b07e0e5.min.js:1)
    at Fo (vendors~main-chunk-d1f09bab0102d8143c16.min.js:136)
    at Ks (vendors~main-chunk-d1f09bab0102d8143c16.min.js:136)
    at Bs (vendors~main-chunk-d1f09bab0102d8143c16.min.js:136)
    at Ns (vendors~main-chunk-d1f09bab0102d8143c16.min.js:136)
    at Ds (vendors~main-chunk-d1f09bab0102d8143c16.min.js:136)
    at vendors~main-chunk-d1f09bab0102d8143c16.min.js:136
    at t.unstable_runWithPriority (vendors~main-chunk-d1f09bab0102d8143c16.min.js:144)
    at li (vendors~main-chunk-d1f09bab0102d8143c16.min.js:136)

Expected results:
should not get the blank page

Additional info:

--- Additional comment from Paul Weil on 2020-06-22 17:02:30 UTC ---

Since we are past final freeze at this point we need to queue this up for 4.5.z.  Moving it to 4.6.