fix(weather): non-finite numbers no longer raise

deg, num, duration and moon_icon now return their missing-value
placeholder for NaN, inf and out-of-range input instead of raising from
%d or utf8.char. sun_t clamps NaN to 0 and age_str returns ? for a NaN
age. Drops the dead -0 fold in deg and fixes a mislabelled assertion.

Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>

1 files changed, 18 insertions, 9 deletions

diff --git a/lib/weather.lua b/lib/weather.lua
index aea630e..d4b1460 100644
--- a/lib/weather.lua
+++ b/lib/weather.lua
@@ -76,22 +76,25 @@ function M.describe(code)
   return DESCRIBE[code] or 'Unknown'
 end
 
-local function round(v) return math.floor(v + 0.5) end
+-- Nearest integer, or nil when v is NaN, infinite or too big for an integer:
+-- %d and utf8.char raise on those, and a raise is a blank dashboard.
+local function round(v) return math.tointeger(math.floor(v + 0.5)) end
 
 -- A temperature as the cards print it. Missing is '--', never '0': zero is a
--- legitimate reading. The '-0' a value just under zero would round to is
--- folded into '0'.
+-- legitimate reading.
 function M.deg(v)
   if type(v) ~= 'number' then return '--' end
   local r = round(v)
-  if r == 0 then r = 0 end
+  if not r then return '--' end
   return string.format('%d\u{00B0}', r)
 end
 
 -- A rounded number with an optional suffix, or '--'.
 function M.num(v, suffix)
   if type(v) ~= 'number' then return '--' end
-  return string.format('%d', round(v)) .. (suffix or '')
+  local r = round(v)
+  if not r then return '--' end
+  return string.format('%d', r) .. (suffix or '')
 end
 
 -- The fetcher asks Open-Meteo for km/h or mph to match UNITS.
@@ -101,8 +104,11 @@ end
 
 -- Seconds as '10h 28m'.
 function M.duration(s)
-  if type(s) ~= 'number' or s < 0 then return '--' end
-  return string.format('%dh %02dm', math.floor(s / 3600), math.floor(s % 3600 / 60))
+  -- ponytail: anything over 1e9 s (about 31 years) is bad data, not a duration.
+  if type(s) ~= 'number' or not (s >= 0 and s < 1e9) then return '--' end
+  local h, m = math.tointeger(math.floor(s / 3600)), math.tointeger(math.floor(s % 3600 / 60))
+  if not (h and m) then return '--' end
+  return string.format('%dh %02dm', h, m)
 end
 
 -- Threshold role names, which index the palette (colors.ok and so on).
@@ -136,7 +142,9 @@ end
 -- One of the 28 Nerd Font moon glyphs, U+E38D (new) to U+E3A8, in phase order.
 function M.moon_icon(phase)
   if type(phase) ~= 'number' then return M.ICON.unknown end
-  return utf8.char(0xE38D + round(phase * 28) % 28)
+  local r = round(phase * 28)
+  if not r then return M.ICON.unknown end
+  return utf8.char(0xE38D + r % 28)
 end
 
 -- Eight compass points. The half-step offset is what makes north straddle
@@ -160,7 +168,7 @@ function M.sun_t(now, sunrise, sunset)
   local span = sunset - sunrise
   if span <= 0 then return 0 end   -- polar day/night or bad data: no division
   local t = (now - sunrise) / span
-  if t < 0 then return 0 elseif t > 1 then return 1 end
+  if not (t >= 0) then return 0 elseif t > 1 then return 1 end
   return t
 end
 
@@ -228,6 +236,7 @@ end
 function M.age_str(dt, now)
   if type(dt) ~= 'number' or type(now) ~= 'number' then return '?' end
   local s = now - dt
+  if s ~= s then return '?' end
   if s < 0 then s = 0 end
   if s < 3600 then return math.floor(s / 60) .. 'm' end
   if s < 86400 then return math.floor(s / 3600) .. 'h' end