pmdalmsensors, qa/1480: handle sensor read failures gracefully

qa/1480

@@ -93,7 +93,7 @@ END				{ print int(sum+0.5) }'`
 echo "pminfo -f lmsensors output:" >> $seq_full
 
 PMDA=`pminfo -f lmsensors | tee -a $seq_full | grep '^  *value ' | \
-	awk '{ sum += $2 } END { print sum }'`
+	awk '{ sum += $2 } END { print sum+0 }'`
 
 if _within_tolerance "Expecting $SENS +- 10%" $PMDA $SENS 10%; then
     echo -n "The output of the 'sensors -u' values differs not more than 10% "

src/pmdas/lmsensors/pmdalmsensors.python

@@ -53,7 +53,13 @@ def lmsensors_get(chip=None):
             if chip:
                 cmd.append(chip)
             p = subprocess.Popen(cmd, stdout=subprocess.PIPE, stderr=devnull)
-            output = json.loads(re.sub("[0-9]_", "_", p.communicate()[0].decode("utf-8")))
+            raw = p.communicate()[0].decode("utf-8")
+            try:
+                output = json.loads(re.sub("[0-9]_", "_", raw))
+            except (json.JSONDecodeError, ValueError):
+                if chip:
+                    return
+                raise
 
         if args.debug_value and args.debug_value >= 0:
             print("function lmsensors_get(), json object after removing redundant naming:\n", output)