into-array fails for sequences starting with nil

done

No search through the sequence will pass screening, please just add a nil check.

Comment made by: pbwolf

Searching through the sequence for a non-null item is not consistent with into-array's docstring. The docstring says, "The array's component type is type if provided, or the type of the first value in aseq if present, or Object." In keeping with the docstring, wouldn't a null first item suggest an array of Object?

Working harder than that (by searching the sequence) only delays the inevitable: a whole sequence of nulls producing an Object array, instead of an array of the type the programmer expected, and triggering a run-time crash.

In summary: this patch goes farther than necessary, but even so, it does not cure the risk of unexpected results from nulls. A simpler remedy – returning an array of Object if the first item is null – would be consistent with the docstring and avoid raising unfounded expectations. Adding a statement that null is of type Object to the docstring could help programmers avoid falling into the trap.

uploading patch v1 (adding nil as a cons-able element in will also bring this out, but I don't want to make the one patch depend on the other)