Rule for x-ms-enum crashes when "name" property is missing.

[tjprescott]

The following Swagger causes LintDiff to crash with a fatal error:

The error is:
openapiValidatorPluginFunc: Failed validating:TypeError: Cannot read property 'toLowerCase' of undefined Location

Here's the failing CI run:
https://github.com/Azure/azure-rest-api-specs/pull/27356/checks?check_run_id=20396982945

Per the specification for x-ms-enum, name is an optional field, so any rule that is operating on x-ms-enum needs to have appropriate logic. In this case, the rule seems to be assuming name exists and calling toLowerCase on it, resulting in the fatal crash.

[mikeharder]

Root cause documented at Azure/azure-sdk-tools#7602

[mikeharder]

I this this code just needs to no-op if name is undefinted:

azure-openapi-validator/packages/rulesets/src/native/legacyRules/UniqueXmsEnumName.ts

Lines 23 to 24 in 2fbba6d

	if (section.value["x-ms-enum"] && isValidEnum(section.value)) {
	const enumName = section.value["x-ms-enum"].name.toLowerCase()

[konrad-jamrozik]

Yeah so probably, in pseudocode:

if (section.value["x-ms-enum"] && isValidEnum(section.value)) {

-->

if (section.value["x-ms-enum"] && isValidEnum(section.value) && section.value["x-ms-enum"] is defined) {

[mikeharder]

if (section.value["x-ms-enum"] && isValidEnum(section.value) && section.value["x-ms-enum"].name is defined) {

Need to check if name is defined

[konrad-jamrozik]

Should be fixed now.

[mikeharder]

Swagger LintDiff is now passing for Azure/azure-rest-api-specs#27356.