fix: Avoid race condition error on multi-process communication (#204)

lib/util.js

@@ -460,6 +460,7 @@ async function toInMemoryBase64 (srcPath, opts = {}) {
  */
 function getLockFileGuard (lockFile, opts = {timeout: 120}) {
   const lock = B.promisify(_lockfile.lock);
+  const performLock = async () => await lock(lockFile, {wait: opts.timeout * 1000});
   const check = B.promisify(_lockfile.check);
   const unlock = B.promisify(_lockfile.unlock);
 
@@ -469,9 +470,17 @@ function getLockFileGuard (lockFile, opts = {timeout: 120}) {
       // on the same spin of the event loop can also initiate a lock. If the lockfile does exist
       // then just use the regular async 'lock' method which will wait on the lock.
       if (!_lockfile.checkSync(lockFile)) {
-        _lockfile.lockSync(lockFile);
+        try {
+          _lockfile.lockSync(lockFile);
+        } catch (e) {
+          // Avoid cross-process race condition
+          if (!_.includes(e.message, 'EEXIST')) {
+            throw e;
+          }
+          await performLock();
+        }
       } else {
-        await lock(lockFile, {wait: opts.timeout * 1000});
+        await performLock();
       }
     } catch (e) {
       throw new Error(`Could not acquire lock on ${lockFile}. Original error: ${e}`);