lint: Don't assign values that will never be used

No bugs here, but giving an initial value can hide cases where we fail
to set a value. Use an assert instead so we can see errors if we change
and break this code.

Except break_next which goes out of scope after it's assigned (I guess
it used to be outside the loop).

.luacheckrc

@@ -4,7 +4,6 @@ return {
         "211", -- Unused local variable.
         "212/self", -- Unused argument self.
         "213", -- Unused loop variable.
-        "311", -- Value assigned to a local variable is unused.
         "631", -- Line is too long.
     },
     files = {

colour.lua

@@ -136,7 +136,7 @@ function colour.rgb_to_hsl(r, g, b)
 	local l, d = max + min, max - min
 	local s = d / (l > 1 and (2 - l) or l)
 	l = l / 2
-	local h = nil --depends on below
+	local h --depends on below
 	if max == r then
 		h = (g - b) / d
 		if g < b then h = h + 6 end
@@ -145,6 +145,7 @@ function colour.rgb_to_hsl(r, g, b)
 	else
 		h = (r - g) / d + 4
 	end
+	assert(h)
 	return h / 6, s, l
 end
 

intersect.lua

@@ -186,7 +186,7 @@ function intersect.line_line_collide(a_start, a_end, a_rad, b_start, b_end, b_ra
 	local numerb = dx1 * dyab - dy1 * dxab
 
 	--check coincident lines
-	local intersected = "none"
+	local intersected
 	if
 		math.abs(numera) < COLLIDE_EPS and
 		math.abs(numerb) < COLLIDE_EPS and
@@ -215,6 +215,7 @@ function intersect.line_line_collide(a_start, a_end, a_rad, b_start, b_end, b_ra
 			end
 		end
 	end
+	assert(intersected)
 
 	if intersected == "both" then
 		--simply displace along A normal

pretty.lua

@@ -153,7 +153,6 @@ function pretty._process(input, config, processing_state)
 			end
 			if break_next then
 				table.insert(line_chunks, table.remove(chunks, 1))
-				break_next = false
 			end
 		end
 		chunks = line_chunks