refactor storageSlot

libs/remix-debug/src/storage/storageResolver.js

@@ -61,10 +61,12 @@ class StorageResolver {
    * @param {String} - address - lookup address
    * @param {Function} - callback - {key, hashedKey, value} -
    */
-  storageSlot (slot, tx, stepIndex, address, callback) {
+  storageSlot (slot, tx, stepIndex, address) {
+    return new Promise((resolve, reject) => {
       this.storageRangeInternal(this, slot, tx, stepIndex, address).then((storage) => {
-      callback(null, storage[slot] !== undefined ? storage[slot] : null)
-    }).catch(callback)
+        resolve(storage[slot] !== undefined ? storage[slot] : null)
+      }).catch(reject)
+    })
   }
 
   /**

libs/remix-debug/src/storage/storageViewer.js

@@ -46,13 +46,9 @@ class StorageViewer {
     if (this.storageChanges[hashed]) {
       return callback(null, this.storageChanges[hashed])
     }
-    this.storageResolver.storageSlot(hashed, this.context.tx, this.context.stepIndex, this.context.address, (error, storage) => {
-      if (error) {
-        callback(error)
-      } else {
+    this.storageResolver.storageSlot(hashed, this.context.tx, this.context.stepIndex, this.context.address).then((storage) => {
       callback(null, storage)
-      }
-    })
+    }).catch(callback)
   }
 
   /**