[bugfix] Nil pointer deref

[edznux-dd]

Associated issue here: #205.

This PR creates a reproducer and a bug fix for a nil dereference crash:

--- FAIL: TestRegressionNilDeref (0.00s)
panic: runtime error: invalid memory address or nil pointer dereference [recovered]
	panic: runtime error: invalid memory address or nil pointer dereference
[signal SIGSEGV: segmentation violation code=0x1 addr=0x10 pc=0x61ff82]

I believe the nil check need to be done in multiple other places and thus, maybe a more generic solution is warranted, but for the time being, that might be already an improvement :)

[Copilot]

Pull Request Overview

This PR addresses a nil pointer dereference in WhereClause by adding guards in BuildWithFlavor and AddWhereClause, and introduces a regression test to ensure nil receivers don’t panic.

• Add wc == nil check in BuildWithFlavor
• Guard against nil wc in AddWhereClause
• Add TestNilPointerWhere to validate nil receiver safety

Reviewed Changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 1 comment.

File	Description
whereclause.go	Added nil checks in BuildWithFlavor and AddWhereClause methods
select_test.go	Added TestNilPointerWhere to catch nil receiver panics

Comments suppressed due to low confidence (1)

select_test.go:421

• [nitpick] This test invokes the build methods but includes no assertions. Add checks on the returned SQL string and args slice to ensure they match expected defaults and to guard against regressions.

func TestNilPointerWhere(t *testing.T) {

[Copilot]

Returning nil here may break chaining when the receiver is nil. Consider returning the non-nil whereClause argument (or a new empty WhereClause) to allow fluent calls without panicking or losing the chain.

Suggested change

	return nil
	return NewWhereClause()