Crash in `getRootDeclaration` when both global namespace and `export as namespace` exist

TypeScript Version: 3.2.0-dev.20181106

Code

declare global { namespace N {} }
export = N;
export as namespace N;

Expected behavior:

No crash.

Actual behavior:

TypeError: Cannot read property 'kind' of undefined
    at getRootDeclaration (typescript\lib\tsc.js:8182:21)
    at Object.isCatchClauseVariableDeclarationOrBindingElement (typescript\lib\tsc.js:6311:20)
    at getTypeOfVariableOrParameterOrPropertyWorker (typescript\lib\tsc.js:29148:20)
    at getTypeOfVariableOrParameterOrProperty (typescript\lib\tsc.js:29132:48)
    at getTypeOfSymbol (typescript\lib\tsc.js:29401:24)
    at checkIdentifier (typescript\lib\tsc.js:37975:49)
    at checkExpressionWorker (typescript\lib\tsc.js:42937:28)
    at checkExpression (typescript\lib\tsc.js:42913:42)
    at checkExpressionCached (typescript\lib\tsc.js:42796:38)
    at markAliasSymbolAsReferenced (typescript\lib\tsc.js:26588:21)

Discovered in business-rules-engine on DefinitelyTyped.