diff --git a/package-lock.json b/package-lock.json
index 0ba8b36ddf..690dad203f 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -4096,9 +4096,9 @@
       }
     },
     "flow-bin": {
-      "version": "0.83.0",
-      "resolved": "https://registry.npmjs.org/flow-bin/-/flow-bin-0.83.0.tgz",
-      "integrity": "sha512-1K83EL/U9Gh0BaXPKkZe6TRizSmNSKx9Wuws1c8gh7DJEwiburtCxYT+4o7in1+GnNEm3CZWnbnVV8n9HMpiDA==",
+      "version": "0.91.0",
+      "resolved": "https://registry.npmjs.org/flow-bin/-/flow-bin-0.91.0.tgz",
+      "integrity": "sha512-j+L+xNiUYnZZ27MjVI0y2c9474ZHOvdSQq0Tjwh56mEA7tfxYqp5Dcb6aZSwvs3tGMTjCrZow9aUlZf3OoRyDQ==",
       "dev": true
     },
     "follow-redirects": {
diff --git a/package.json b/package.json
index 6a77179189..06a103f5be 100644
--- a/package.json
+++ b/package.json
@@ -57,7 +57,7 @@
     "deep-diff": "1.0.2",
     "eslint": "^5.0.0",
     "eslint-plugin-flowtype": "^3.0.0",
-    "flow-bin": "0.83.0",
+    "flow-bin": "0.91.0",
     "gaze": "1.1.3",
     "husky": "^1.0.0-rc.13",
     "jasmine": "3.1.0",
diff --git a/src/Adapters/Storage/Postgres/PostgresStorageAdapter.js b/src/Adapters/Storage/Postgres/PostgresStorageAdapter.js
index dcfd34b877..a24aad0e87 100644
--- a/src/Adapters/Storage/Postgres/PostgresStorageAdapter.js
+++ b/src/Adapters/Storage/Postgres/PostgresStorageAdapter.js
@@ -1963,12 +1963,14 @@ export class PostgresStorageAdapter implements StorageAdapter {
     const wherePattern =
       where.pattern.length > 0 ? `WHERE ${where.pattern}` : '';
     const qs = `SELECT count(*) FROM $1:name ${wherePattern}`;
-    return this._client.one(qs, values, a => +a.count).catch(error => {
-      if (error.code !== PostgresRelationDoesNotExistError) {
-        throw error;
-      }
-      return 0;
-    });
+    return this._client
+      .one(qs, values, a => +a.count)
+      .catch(error => {
+        if (error.code !== PostgresRelationDoesNotExistError) {
+          throw error;
+        }
+        return 0;
+      });
   }
 
   distinct(
@@ -2093,32 +2095,34 @@ export class PostgresStorageAdapter implements StorageAdapter {
             index += 1;
             continue;
           }
-          if (value.$sum) {
-            if (typeof value.$sum === 'string') {
-              columns.push(`SUM($${index}:name) AS $${index + 1}:name`);
-              values.push(transformAggregateField(value.$sum), field);
+          if (typeof value === 'object') {
+            if (value.$sum) {
+              if (typeof value.$sum === 'string') {
+                columns.push(`SUM($${index}:name) AS $${index + 1}:name`);
+                values.push(transformAggregateField(value.$sum), field);
+                index += 2;
+              } else {
+                countField = field;
+                columns.push(`COUNT(*) AS $${index}:name`);
+                values.push(field);
+                index += 1;
+              }
+            }
+            if (value.$max) {
+              columns.push(`MAX($${index}:name) AS $${index + 1}:name`);
+              values.push(transformAggregateField(value.$max), field);
+              index += 2;
+            }
+            if (value.$min) {
+              columns.push(`MIN($${index}:name) AS $${index + 1}:name`);
+              values.push(transformAggregateField(value.$min), field);
+              index += 2;
+            }
+            if (value.$avg) {
+              columns.push(`AVG($${index}:name) AS $${index + 1}:name`);
+              values.push(transformAggregateField(value.$avg), field);
               index += 2;
-            } else {
-              countField = field;
-              columns.push(`COUNT(*) AS $${index}:name`);
-              values.push(field);
-              index += 1;
             }
-          }
-          if (value.$max) {
-            columns.push(`MAX($${index}:name) AS $${index + 1}:name`);
-            values.push(transformAggregateField(value.$max), field);
-            index += 2;
-          }
-          if (value.$min) {
-            columns.push(`MIN($${index}:name) AS $${index + 1}:name`);
-            values.push(transformAggregateField(value.$min), field);
-            index += 2;
-          }
-          if (value.$avg) {
-            columns.push(`AVG($${index}:name) AS $${index + 1}:name`);
-            values.push(transformAggregateField(value.$avg), field);
-            index += 2;
           }
         }
       } else {