Get an error when collecting examples

[sipayRT]

for example, you have an example 00-all.bemjson.js:

1. add 00-all.blocks folder where you will add some blocks for your examples
2. run server and collect example
3. delete 00-all.blocks
4. try to collect example again
   I got an error such as:

Error: ENOENT, no such file or directory '/Users/sipayrt/sites/promo/islands-promo-bc/desktop.examples/button/00-all/blocks'
    at Object.fs.readdirSync (fs.js:654:18)
    at module.exports.inherit.load (/Users/sipayrt/sites/promo/islands-promo-bc/node_modules/enb-bem-techs/lib/levels/level.js:212:28)
    at /Users/sipayrt/sites/promo/islands-promo-bc/node_modules/enb-bem-techs/techs/levels.js:126:38
    at Array.map (native)
    at /Users/sipayrt/sites/promo/islands-promo-bc/node_modules/enb-bem-techs/techs/levels.js:125:42
    at Array.3 (/Users/sipayrt/sites/promo/islands-promo-bc/node_modules/enb/node_modules/vow/lib/vow.js:202:56)
    at Object.callFns [as _onImmediate] (/Users/sipayrt/sites/promo/islands-promo-bc/node_modules/enb/node_modules/vow/lib/vow.js:462:35)
    at processImmediate [as _immediateCallback] (timers.js:330:15)