*.json files with no validKeys blow up TypeError: Cannot read property '0' of null in ExportDefaultDeclaration.prototype.render

[btakita]

I'm packaging an import from mime-db, which loads a json file.

https://github.com/jshttp/mime-db/blob/master/db.json

Stack trace

Cannot read property '0' of null
TypeError: Cannot read property '0' of null
at ExportDefaultDeclaration.render (/home/user/project/node_modules/rollup/src/ast/nodes/ExportDefaultDeclaration.js:57:4)
at Module.render (/home/user/project/node_modules/rollup/src/Module.js:320:8)
at /home/user/project/node_modules/rollup/src/Bundle.js:376:17
at Array.forEach (native)
at Bundle.render (/home/user/project/node_modules/rollup/src/Bundle.js:375:16)
at generate (/home/user/project/node_modules/rollup/src/rollup.js:75:30)
at Object.result.write (/home/user/project/node_modules/rollup/src/rollup.js:103:9)
at /home/user/project/node_modules/rollup-watch/dist/rollup-watch.cjs.js:162:21
Type rollup --help for help, or visit https://github.com/rollup/rollup/wiki

See rollup/rollup-plugin-json#19

[kzc]

When I changed ExportDefaultDeclaration I assumed that acorn would produce the AST. But it appears that the AST is generated by rollup-plugin-json in this case and something is amiss.

Can you confirm that this rollup patch fixes the problem for you?

--- a/src/ast/nodes/ExportDefaultDeclaration.js
+++ b/src/ast/nodes/ExportDefaultDeclaration.js
@@ -53,7 +53,7 @@ export default class ExportDefaultDeclaration extends Node {
                let declaration_start;
                if ( this.declaration ) {
                        const statementStr = code.original.slice( this.start, this.end );
-                       declaration_start = this.start + statementStr.match(/^export\s+default\s*/)[0].length;
+                       declaration_start = this.start + statementStr.match(/^\s*export\s+default\s+/)[0].length;
                }
 
                if ( this.shouldInclude || this.declaration.activated ) {

If it doesn't work could you please post the value of JSON.stringify(statementStr)?

[kzc]

Likely fix: #1152

[Rich-Harris]

Fixed on both ends now, so I'll close this

[yairEO]

@Rich-Harris

Regular user here reporting. been using Rollup for over a year with Gulp.
I'm getting this error (in the title) even after updating to v0.40.0 (with Node v5.8.0):

[14:44:16] Rollup [catch]:  TypeError: Cannot read property '0' of null
    at ExportDefaultDeclaration.render (C:\www\UI\BUILD\node_modules\rollup\dist\rollup.js:6225:82)
    at Module.render (C:\www\UI\BUILD\node_modules\rollup\dist\rollup.js:7767:8)
    at C:\www\UI\BUILD\node_modules\rollup\dist\rollup.js:9080:23
    at Array.forEach (native)
    at Bundle.render (C:\www\UI\BUILD\node_modules\rollup\dist\rollup.js:9079:22)
    at Object.generate (C:\www\UI\BUILD\node_modules\rollup\dist\rollup.js:9316:26)
    at C:\www\UI\BUILD\gulpfile.js:657:33
    at lib$es6$promise$$internal$$tryCatch (C:\www\UI\BUILD\node_modules\es6-promise\dist\es6-promise.js:362:16)
    at lib$es6$promise$$internal$$invokeCallback (C:\www\UI\BUILD\node_modules\es6-promise\dist\es6-promise.js:374:17)
    at lib$es6$promise$$internal$$publish (C:\www\UI\BUILD\node_modules\es6-promise\dist\es6-promise.js:345:11)
    at lib$es6$promise$asap$$flush (C:\www\UI\BUILD\node_modules\es6-promise\dist\es6-promise.js:119:9)
    at _combinedTickCallback (node.js:370:9)
    at process._tickCallback (node.js:401:11)

And this is the function inside my gulpfile which I wrote to do the rollups:

/**
 * a generic Rollup bundle creator
 * @param  {String} outputPath     [where to save the bundle to (must end with /)]
 * @param  {String} outputFileName [bundle file name]
 * @param  {String} entryFile      [rollup entry file to start scanning from]
 * @return {Object}                [Promise]
 */
function rollupBundle(outputPath, outputFileName, entryFile, bundleOptions){
    bundleOptions = bundleOptions || {};

    return new Promise(function(resolve, reject) {
        outputFileName += '.js';
        var cache;

        rollup({
            entry   : entryFile,
            plugins : rollupPlugins,  // comes from another place within the gulpfile
            cache   : cache
        })
        .then(function (bundle) {
            var bundleSettings = {
                    format    : bundleOptions.format || 'umd',
                //  sourceMap : true,
                    banner    : config.banner
                },
                result = bundle.generate(bundleSettings),
                mapFileName = outputFileName + '.map',
                sourceMappingURL = '\n//# sourceMappingURL='+ mapFileName;

            cache = bundle;

            // if folder does not exists, create it
            if( !fs.existsSync(outputPath) ){
                gutil.log( gutil.colors.black.bgWhite('Creating directory ' + outputPath) );
                fs.mkdirSync(outputPath);
            }

            // save bundle file to disk
            fs.writeFile( outputPath + outputFileName, result.code + (bundleSettings.sourceMap ? sourceMappingURL : ''), function(){
                resolve();
            });

            // save map file to disk
            if( bundleSettings.sourceMap )
                fs.writeFile( outputPath + mapFileName, result.map.toString());
        })
        .catch(function(err){
            gutil.log( gutil.colors.white.bgRed('Rollup [catch]: ', err.stack) );
            resolve();
        })
    });
}

Error stack mentioned line gulpfile.js:657:33 which is:

result = bundle.generate(bundleSettings),

Why do I get this error now?

[kzc]

Fixed in 0.40.1

Allow missing space between export default and declaration (#1218)