When attempting to export a reference that has no author, an exception is thrown with this stack trace:
TypeError: implode(): Argument #1 ($array) must be of type array, string given in implode() (line 223 of modules/contrib/bibcite/modules/bibcite_bibtex/src/Encoder/BibtexEncoder.php).
Drupal\bibcite_bibtex\Encoder\BibtexEncoder->buildLine('author', NULL) (Line: 176)
Drupal\bibcite_bibtex\Encoder\BibtexEncoder->buildEntry(Array) (Line: 146)
Drupal\bibcite_bibtex\Encoder\BibtexEncoder->Drupal\bibcite_bibtex\Encoder\{closure}(Array)
array_map(Object, Array) (Line: 145)
Drupal\bibcite_bibtex\Encoder\BibtexEncoder->encode(Array, 'bibtex', Array) (Line: 43)
Symfony\Component\Serializer\Encoder\ChainEncoder->encode(Array, 'bibtex', Array) (Line: 418)
Symfony\Component\Serializer\Serializer->encode(Array, 'bibtex', Array) (Line: 143)
Symfony\Component\Serializer\Serializer->serialize(Array, 'bibtex') (Line: 75)
Drupal\bibcite_export\Controller\ExportController->processExport(Array, Object, 'bibcite_reference-921-BibTeX') (Line: 113)
Drupal\bibcite_export\Controller\ExportController->export(Object, 'bibcite_reference', Object)
call_user_func_array(Array, Array) (Line: 123)
Drupal\Core\EventSubscriber\EarlyRenderingControllerWrapperSubscriber->Drupal\Core\EventSubscriber\{closure}() (Line: 638)
Drupal\Core\Render\Renderer->executeInRenderContext(Object, Object) (Line: 121)
Drupal\Core\EventSubscriber\EarlyRenderingControllerWrapperSubscriber->wrapControllerExecutionInRenderContext(Array, Array) (Line: 97)
Drupal\Core\EventSubscriber\EarlyRenderingControllerWrapperSubscriber->Drupal\Core\EventSubscriber\{closure}() (Line: 181)
Symfony\Component\HttpKernel\HttpKernel->handleRaw(Object, 1) (Line: 76)
Symfony\Component\HttpKernel\HttpKernel->handle(Object, 1, 1) (Line: 53)
Drupal\Core\StackMiddleware\Session->handle(Object, 1, 1) (Line: 48)
Drupal\Core\StackMiddleware\KernelPreHandle->handle(Object, 1, 1) (Line: 28)
Drupal\Core\StackMiddleware\ContentLength->handle(Object, 1, 1) (Line: 32)
Drupal\big_pipe\StackMiddleware\ContentLength->handle(Object, 1, 1) (Line: 40)
Drupal\ps_ban\BanMiddleware->handle(Object, 1, 1) (Line: 48)
Drupal\Core\StackMiddleware\ReverseProxyMiddleware->handle(Object, 1, 1) (Line: 51)
Drupal\Core\StackMiddleware\NegotiationMiddleware->handle(Object, 1, 1) (Line: 36)
Drupal\Core\StackMiddleware\AjaxPageState->handle(Object, 1, 1) (Line: 51)
Drupal\Core\StackMiddleware\StackedHttpKernel->handle(Object, 1, 1) (Line: 741)
Drupal\Core\DrupalKernel->handle(Object) (Line: 19)
Note that is NO author or editor is provided, or BOTH an author and editor are provided, it exports fine. It's just a problem if ONLY an editor is provided and no author.