ENH make processor not puke if coretemps paths not found

src/modules/processor.lua

@@ -70,7 +70,6 @@ return function(update_freq, config, main_state, common, width, point)
    end
 
    local mk_cores = function(y)
-      local coretemp_paths = cpu.get_coretemp_paths()
       local core_cols = ncores / config.core_rows
       local cores = {}
       for c = 1, ncores do
@@ -85,6 +84,16 @@ return function(update_freq, config, main_state, common, width, point)
             * math.floor((c - 1) / core_cols)
          cores[c] = create_core(dial_x, dial_y)
       end
+      local coretemp_paths = cpu.get_coretemp_paths()
+      local update_coretemps = function() end
+      if coretemp_paths ~= nil then
+         update_coretemps = function()
+            for conky_core_id, path in pairs(coretemp_paths) do
+               local temp = __math_floor(0.001 * i_o.read_file(path, nil, '*n'))
+               common.text_circle_set(cores[conky_core_id].coretemp, temp)
+            end
+         end
+      end
       local update = function()
          for _, load_data in pairs(mod_state) do
             compound_dial.set(
@@ -93,10 +102,7 @@ return function(update_freq, config, main_state, common, width, point)
                load_data.percent_active * 100
             )
          end
-         for conky_core_id, path in pairs(coretemp_paths) do
-            local temp = __math_floor(0.001 * i_o.read_file(path, nil, '*n'))
-            common.text_circle_set(cores[conky_core_id].coretemp, temp)
-         end
+         update_coretemps()
       end
       local static = function(cr)
          for i = 1, #cores do

src/sys.lua

@@ -184,11 +184,10 @@ M.get_cpu_number = function()
    return tonumber(i_o.execute_cmd('nproc', nil, '*n'))
 end
 
--- TODO what if this fails?
 local get_coretemp_dir = function()
    i_o.assert_exe_exists('grep')
    local s = i_o.execute_cmd('grep -l \'^coretemp$\' /sys/class/hwmon/*/name')
-   return dirname(s)
+   if s == nil then return else return dirname(s) end
 end
 
 -- map cores to integer values starting at 1; this is necessary since some cpus
@@ -226,6 +225,7 @@ end
 
 M.get_coretemp_paths = function()
    local d = get_coretemp_dir()
+   if d == nil then return end
    i_o.assert_exe_exists('grep')
    local s = i_o.execute_cmd(string.format('grep Core %s/temp*_label', d))
    local ps = {}