query: turn invalid query string into valid simple query value

Parsing `title: "hello\"` results :
- before `Parse error on line 1: Expecting 'QUOTE', got '1'`
- now `{ type: simple, key: undefined, value: 'title: "hello\\"' }`

src/queries/query.js

@@ -662,7 +662,16 @@
       return new Query(key_schema);
     }
     if (typeof object === "string") {
-      object = parseStringToObject(object);
+      try {
+        object = parseStringToObject(object);
+      } catch (error) {
+        if (error.hash && error.hash.expected &&
+            error.hash.expected.length === 1 &&
+            error.hash.expected[0] === "'QUOTE'") {
+          return new query_class_dict.simple({value: object});
+        }
+        throw error;
+      }
     }
     if (typeof (object || {}).type === "string" &&
         query_class_dict[object.type]) {

test/queries/tests.js

@@ -377,6 +377,22 @@
       "{simple query ending with backslash}.toString()"
     );
 
+    deepEqual(
+      jIO.QueryFactory.create('identifier: "\\"').toJSON(),
+      {
+        "key": undefined,  // could not exist as JSON.stringify removes it
+        "type": "simple",
+        "value": 'identifier: "\\"',
+      },
+      "'identifier: \"\\\"'.toJSON()"
+    );
+
+    deepEqual(
+      jIO.QueryFactory.create('identifier: "\\"').toString(),
+      ' "identifier: "\\""',
+      "'identifier: \"\\\"'.toString()"
+    );
+
   });
 
   test('Docs with space, tab, and newline', function () {