Handle a non-impossible empty argv in loadServerConfigFromString().

Usually this does not happens since we trim for " \t\r\n", but if there
are other chars that return true with isspace(), we may end with an
empty argv. Better to handle the condition in an explicit way.

src/config.c

@@ -68,7 +68,7 @@ void loadServerConfigFromString(char *config) {
         linenum = i+1;
         lines[i] = sdstrim(lines[i]," \t\r\n");
 
-        /* Skip comments and blank lines*/
+        /* Skip comments and blank lines */
         if (lines[i][0] == '#' || lines[i][0] == '\0') continue;
 
         /* Split into arguments */
@@ -77,6 +77,12 @@ void loadServerConfigFromString(char *config) {
             err = "Unbalanced quotes in configuration line";
             goto loaderr;
         }
+
+        /* Skip this line if the resulting command vector is empty. */
+        if (argc == 0) {
+            sdsfreesplitres(argv,argc);
+            return;
+        }
         sdstolower(argv[0]);
 
         /* Execute config directives */