fix: potential error in isTryCatchStatement

In some cases the `bodyArg.handler.param` can have the value `null` which causes the line on 42/43 to cause a runtime exception as it tries to access a property `name` on `null`

Author: weyert

lib/rules/detect-unhandled-async-errors.js

@@ -39,6 +39,7 @@ function isIfWithReturn (bodyArg) {
 function isTryCatchStatement (bodyArg) {
   return bodyArg.type === 'TryStatement' &&
     bodyArg.handler.type === 'CatchClause' &&
+    bodyArg.handler.param &&
     /^(e|err|error|Error|anySpecificError)$/.test(bodyArg.handler.param.name)
 }