Online PHP editor | output for 2V6W3

Output for 8.3.0 - 8.3.6: Fatal error: Uncaught TypeError: array_merge(): Argument #3 must be of type array, false given in /in/2V6W3:5 Stack trace: #0 /in/2V6W3(5): array_merge(Array, Array, false) #1 {main} thrown in /in/2V6W3 on line 5
Process exited with code 255.
Output for 8.0.0 - 8.0.30, 8.1.0 - 8.1.28, 8.2.0 - 8.2.18: Fatal error: Uncaught TypeError: array_merge(): Argument #3 must be of type array, bool given in /in/2V6W3:5 Stack trace: #0 /in/2V6W3(5): array_merge(Array, Array, false) #1 {main} thrown in /in/2V6W3 on line 5
Process exited with code 255.
Output for 7.3.0 - 7.3.33, 7.4.0 - 7.4.33: Warning: array_merge(): Expected parameter 3 to be an array, bool given in /in/2V6W3 on line 5 NULL
Output for 5.0.0 - 5.0.5, 5.1.0 - 5.1.6, 5.2.0 - 5.2.17, 5.3.0 - 5.3.29, 5.4.0 - 5.4.45, 5.5.0 - 5.5.38, 5.6.0 - 5.6.40, 7.0.0 - 7.0.33, 7.1.0 - 7.1.33, 7.2.0 - 7.2.33: Warning: array_merge(): Argument #3 is not an array in /in/2V6W3 on line 5 NULL
Output for 4.3.0 - 4.3.11, 4.4.0 - 4.4.9: array(3) { [0]=> string(1) "e" [1]=> string(1) "f" [2]=> bool(false) }