nonce-tracker - wrap nonce calculations in try-catch and release lock on error

app/scripts/controllers/transactions/nonce-tracker.js

@@ -50,6 +50,7 @@ class NonceTracker {
     await this._globalMutexFree()
     // await lock free, then take lock
     const releaseLock = await this._takeMutex(address)
+    try {
       // evaluate multiple nextNonce strategies
       const nonceDetails = {}
       const networkNonceResult = await this._getNetworkNextNonce(address)
@@ -73,6 +74,11 @@ class NonceTracker {
 
       // return nonce and release cb
       return { nextNonce, nonceDetails, releaseLock }
+    } catch (err) {
+      // release lock if we encounter an error
+      releaseLock()
+      throw err
+    }
   }
 
   async _globalMutexFree () {