Fix blockAtEntityCursor returning null when yaw or pitch is 0

[SirYadav1]

Fixes #3935

bot.blockAtEntityCursor() (and blockAtCursor) incorrectly returned null whenever the entity had yaw === 0 or pitch === 0, because the guard used truthiness checks (!entity.yaw / !entity.pitch). A value of 0 is a perfectly valid orientation (e.g. looking level = pitch 0, facing north = yaw 0), so the ray trace was being skipped.

Change

lib/plugins/ray_trace.js — replaced the truthiness guard with explicit null checks:

// before
if (!entity.position || !entity.height || !entity.pitch || !entity.yaw) return null
// after
if (entity.position == null || entity.height == null || entity.pitch == null || entity.yaw == null) return null

Test

Added blockAtEntityCursor handles zero yaw and pitch (#3935) to test/internalTest.js. It places a column of gold blocks in the cursor direction, sets yaw = 0 and pitch = 0, and asserts the block is returned. The test fails on the old code (returns null) and passes on the fix, across all tested versions (1.21.4 – 26.1).

Verification

Also verified against a live 1.21.11 Paper server (intel-node2.zyphron.cloud:20013): with the fix the ray cast is actually executed instead of early-returning.