feat(ajv): Keep validation type while using errorMessage

When `errorMessage` is used, ajv returns a special error object,`error.keyword='errorMessage'`,
and keeps original validation errors in `error.errors` field.
The proposed changes normalze the ajv validation errors,
so the resolver returns original error types, like `required` and `pattern`
while using custom error messages.

This also fixes react-hook-form#615

ajv/src/__tests__/__fixtures__/data-errors.ts

@@ -0,0 +1,216 @@
+import { JSONSchemaType } from 'ajv';
+import { Field, InternalFieldName } from 'react-hook-form';
+
+interface DataA {
+  username: string;
+  password: string;
+}
+
+export const schemaA: JSONSchemaType<DataA> = {
+  type: 'object',
+  properties: {
+    username: {
+      type: 'string',
+      minLength: 3,
+      errorMessage: {
+        minLength: 'username should be at least three characters long',
+      },
+    },
+    password: {
+      type: 'string',
+      pattern: '.*[A-Z].*',
+      minLength: 8,
+      errorMessage: {
+        pattern: 'One uppercase character',
+        minLength: 'passwords should be at least eight characters long',
+      },
+    },
+  },
+  required: ['username', 'password'],
+  additionalProperties: false,
+  errorMessage: {
+    required: {
+      username: 'username field is required',
+      password: 'password field is required',
+    },
+  },
+};
+
+export const validDataA: DataA = {
+  username: 'kt666',
+  password: 'validPassword',
+};
+
+export const invalidDataA = {
+  username: 'kt',
+  password: 'invalid',
+};
+
+export const undefinedDataA = {
+  username: undefined,
+  password: undefined,
+};
+
+export const fieldsA: Record<InternalFieldName, Field['_f']> = {
+  username: {
+    ref: { name: 'username' },
+    name: 'username',
+  },
+  password: {
+    ref: { name: 'password' },
+    name: 'password',
+  },
+  email: {
+    ref: { name: 'email' },
+    name: 'email',
+  },
+  birthday: {
+    ref: { name: 'birthday' },
+    name: 'birthday',
+  },
+};
+
+// examples from [ajv-errors](https://github.com/ajv-validator/ajv-errors)
+
+interface DataB {
+  foo: number;
+}
+
+export const schemaB: JSONSchemaType<DataB> = {
+  type: 'object',
+  required: ['foo'],
+  properties: {
+    foo: { type: 'integer' },
+  },
+  additionalProperties: false,
+  errorMessage: 'should be an object with an integer property foo only',
+};
+
+export const validDataB: DataB = { foo: 666 };
+export const invalidDataB = { foo: 'kt', bar: 6 };
+export const undefinedDataB = { foo: undefined };
+
+interface DataC {
+  foo: number;
+}
+
+export const schemaC: JSONSchemaType<DataC> = {
+  type: 'object',
+  required: ['foo'],
+  properties: {
+    foo: { type: 'integer' },
+  },
+  additionalProperties: false,
+  errorMessage: {
+    type: 'should be an object',
+    required: 'should have property foo',
+    additionalProperties: 'should not have properties other than foo',
+  },
+};
+
+export const validDataC: DataC = { foo: 666 };
+export const invalidDataC = { foo: 'kt', bar: 6 };
+export const undefinedDataC = { foo: undefined };
+export const invalidTypeDataC = 'something';
+
+interface DataD {
+  foo: number;
+  bar: string;
+}
+
+export const schemaD: JSONSchemaType<DataD> = {
+  type: 'object',
+  required: ['foo', 'bar'],
+  properties: {
+    foo: { type: 'integer' },
+    bar: { type: 'string' },
+  },
+  errorMessage: {
+    type: 'should be an object', // will not replace internal "type" error for the property "foo"
+    required: {
+      foo: 'should have an integer property "foo"',
+      bar: 'should have a string property "bar"',
+    },
+  },
+};
+
+export const validDataD: DataD = { foo: 666, bar: 'kt' };
+export const invalidDataD = { foo: 'kt', bar: 6 };
+export const undefinedDataD = { foo: undefined, bar: undefined };
+export const invalidTypeDataD = 'something';
+
+interface DataE {
+  foo: number;
+  bar: string;
+}
+
+export const schemaE: JSONSchemaType<DataE> = {
+  type: 'object',
+  required: ['foo', 'bar'],
+  allOf: [
+    {
+      properties: {
+        foo: { type: 'integer', minimum: 2 },
+        bar: { type: 'string', minLength: 2 },
+      },
+      additionalProperties: false,
+    },
+  ],
+  errorMessage: {
+    properties: {
+      foo: 'data.foo should be integer >= 2',
+      bar: 'data.bar should be string with length >= 2',
+    },
+  },
+};
+
+export const validDataE: DataE = { foo: 666, bar: 'kt' };
+export const invalidDataE = { foo: 1, bar: 'k' };
+export const undefinedDataE = { foo: undefined, bar: undefined };
+
+interface DataF {
+  foo: number;
+  bar: string;
+}
+
+export const schemaF: JSONSchemaType<DataF> = {
+  type: 'object',
+  required: ['foo', 'bar'],
+  allOf: [
+    {
+      properties: {
+        foo: { type: 'integer', minimum: 2 },
+        bar: { type: 'string', minLength: 2 },
+      },
+      additionalProperties: false,
+    },
+  ],
+  errorMessage: {
+    type: 'data should be an object',
+    properties: {
+      foo: 'data.foo should be integer >= 2',
+      bar: 'data.bar should be string with length >= 2',
+    },
+    _: 'data should have properties "foo" and "bar" only',
+  },
+};
+
+export const validDataF: DataF = { foo: 666, bar: 'kt' };
+export const invalidDataF = {};
+export const undefinedDataF = { foo: 1, bar: undefined };
+export const invalidTypeDataF = 'something';
+
+export const fieldsRest: Record<InternalFieldName, Field['_f']> = {
+  foo: {
+    ref: { name: 'foo' },
+    name: 'foo',
+  },
+  bar: {
+    ref: { name: 'bar' },
+    name: 'bar',
+  },
+  lorem: {
+    ref: { name: 'lorem' },
+    name: 'lorem',
+  },
+};