coblestone wall connected texture

There are meant to be gaps between walls on top of walls – they do not form a continuous barries (unlike solid blocks on solid blocks).

According to the wiki (I've not tested this) you can shoot arrows through the gaps.

PS. The environment field on the bug report is for your computing environment (OS, Java version, ...) not the biome in Minecraft.

Screenshot is too dark to see anything, but from what little I can see it's all good.

Taking a screenshot? Do it in daylight, btw nothing wrong there. Those "gaps" are ment to be there.