An ReferenceError occured:

ReferenceError: a is not defined
at Object.thisWillCrash (/var/www/webanwendungen-git/framework_projects/vorlesung/helpers/error.js:9:5)
at Object.<anonymous> (/var/www/webanwendungen-git/framework_projects/vorlesung/node_modules/fhw-web/lib/compile.js:88:37)
at Object.helperWrapper (/var/www/webanwendungen-git/framework_projects/vorlesung/node_modules/promised-handlebars/index.js:130:23)
at Object.<anonymous> (/var/www/webanwendungen-git/framework_projects/vorlesung/node_modules/promised-handlebars/lib/utils.js:29:28)
at Object.eval [as main] (eval at createFunctionContext (/var/www/webanwendungen-git/framework_projects/vorlesung/node_modules/handlebars/dist/cjs/handlebars/compiler/javascript-compiler.js:254:23), <anonymous>:4:211)
at main (/var/www/webanwendungen-git/framework_projects/vorlesung/node_modules/handlebars/dist/cjs/handlebars/runtime.js:175:32)
at ret (/var/www/webanwendungen-git/framework_projects/vorlesung/node_modules/handlebars/dist/cjs/handlebars/runtime.js:178:12)
at ret (/var/www/webanwendungen-git/framework_projects/vorlesung/node_modules/handlebars/dist/cjs/handlebars/compiler/compiler.js:526:21)
at prepareAndResolveMarkers (/var/www/webanwendungen-git/framework_projects/vorlesung/node_modules/promised-handlebars/index.js:99:39)
at /var/www/webanwendungen-git/framework_projects/vorlesung/node_modules/promised-handlebars/lib/utils.js:29:28
at /var/www/webanwendungen-git/framework_projects/vorlesung/node_modules/fhw-web/lib/compile.js:238:12