Functionality of array_repeat udf

[jatin510]

Describe the bug

How array_repeat works currently for null as input in array or key:

> SELECT array_repeat(null,0 ) AS repeated_array;
+----------------+
| repeated_array |
+----------------+
| []             |
+----------------+
1 row(s) fetched. 
Elapsed 0.006 seconds.

> SELECT array_repeat(null,1 ) AS repeated_array;
+----------------+
| repeated_array |
+----------------+
| []             |
+----------------+
1 row(s) fetched. 
Elapsed 0.002 seconds.

> SELECT array_repeat(null,2 ) AS repeated_array;
+----------------+
| repeated_array |
+----------------+
| [, ]           |
+----------------+
1 row(s) fetched. 
Elapsed 0.004 seconds.

> SELECT array_repeat(ARRAY[1, 2], null) AS repeated_array;
Internal error: could not cast value to arrow_array::array::primitive_array::PrimitiveArray<arrow_array::types::Int64Type>.
This was likely caused by a bug in DataFusion's code and we would welcome that you file an bug report in our issue tracker

• if we check this out, the length is also not same,
  but above both look same ?

> SELECT ARRAY_LENGTH(array_repeat(null, 0));

+-------------------------------------------+
| array_length(array_repeat(NULL,Int64(0))) |
+-------------------------------------------+
| 0                                         |
+-------------------------------------------+
1 row(s) fetched. 
Elapsed 0.006 seconds.

> SELECT ARRAY_LENGTH(array_repeat(null, 1));
+-------------------------------------------+
| array_length(array_repeat(NULL,Int64(1))) |
+-------------------------------------------+
| 1                                         |
+-------------------------------------------+

To Reproduce

No response

Expected behavior

• both are looking same visually. Is thsi desired behaviour ?

No response

Additional context

[jayzhan211]

empty array [] and array of null with len = 1 [] looks the same but they are different, since we don't output null

SELECT array_repeat(ARRAY[1, 2], null)

I think we can return null for this case

[jatin510]

I think we can return null for this case

This will be a breaking change.
@jayzhan211
cc: @alamb